Implant Terminology










Implant
Terminology
335
The term implant refers to a material introduced into the body to replace or reinforce an
organ or tissue, such as bone chips or endoprostheses (eg, arti cial blood vessels and
joint replacements). Thus, in dentistry the term implantology refers to the placement
of dental implants (parts to replace tooth roots) in the maxilla and mandible to receive
tooth replacements. These tooth root replacement parts are implanted from alloplastic
(foreign to the body) materials into the jaw area to anchor individual teeth or an exten-
sive  xed or removable prosthesis.
Closed implants are surrounded on all sides by the body’s own tissues, for example
closed magnetic implants, joint replacements, or heart valves. Open implants are tissue
replacement components sunk into the body that permanently protrude through the
surface of the body and can form a constant entry portal for germs. The root replacement
parts commonly used in dentistry for af xing dentures are open implants (Fig 9-1).
Implant placement takes place in several stages, starting with history taking, clinical
examination, and radiographs and concluding with the actual surgical procedure. De-
pending on the timing, a distinction can be made between one-stage (single-phase or
one-step) and two-stage (dual-phase or two-step) implant placement.
In one-stage implant placement, the implant is inserted so that the exostructure (im-
plant post/abutment) protrudes through the mucosa during the healing phase and is
functionally loaded by an implant-supported denture immediately after implantation.
No prosthetic replacement is worn for about 2 weeks to ensure that wound healing of
the mucosa is not impeded. In one-stage implantation, one-piece implants are used, and
these can be applied in an edentulous mandible for bar-retained prostheses and  tted in
a single session.

336
Implant Terminology
Fig 9-1 Open implants are replacement tissue parts sunk into
the body with an implant component permanently protruding
through the surface of the body. This provides a constant entry
portal to the inside of the body for disease pathogens. Dental
root replacement parts for xation of dentures are open im-
plants. Closed implants are surrounded on all sides by bodily
tissues, for example closed magnetic implants, replacement
joints, or heart valves. These implants cannot be corroded by
external factors and do not offer any entry portals for patho-
gens.
Superstructure
Implant body
Alveolar bone
Gingiva
Implant abutment
Fixation screw
Implant bed
Fig 9-2 An endosseous implant comprises the endostructure
(the part sunk into the bone, or implant body) and the exo-
structure (the part protruding out of the tissue), onto which the
mesostructure (the component that connects to the prosthetic
replacement) is xed.
Fig 9-3 The abutment is intended to connect the implant to
the superstructure (that is, the tooth replacement). Ball attach-
ments can be used for removable complete dentures, such as
those also tted onto root crowns.

337
Indications for Implants
In two-stage implant placement, the implant is
covered by sutured mucosa and is not function-
ally loaded by a tooth replacement throughout
an unloaded healing phase (about 3 to 6 months)
when direct bony ingrowth (osseointegration) of
the implant is possible. In a second procedure,
the neck of the implant is exposed and the meso-
structure (abutment) is screwed in place. Two-part
implants, in which the endostructure (implant
body) and exostructure (abutment) are separate
(Fig 9-2), are available for this two-stage method.
In two-part implants, the abutment can be aligned
with the prosthetic replacement (Fig 9-3).
The implant bed is the bony cavity for endosse-
ous implants; in the case of mucosal implants, it
is the dimensionally accurate hollow in the muco-
sa into which the implant is inserted. A cavity con-
gruent with the implant is milled into the bone or
punched into the mucosa. Internally cooled im-
plant cutters are available for preparation of the
bony implant bed. These are special bone cutters
for low-speed milling (approximately 200 rpm).
They have a central hole in the cutter shaft for the
coolant, which cools the cutter and the prepara-
tion eld while simultaneously and continuously
rinsing out the bone chips.
Immediate implant placement refers to implan-
tations that are performed directly after tooth ex-
traction and before bony consolidation of the sock-
et. The alveolar bone contour remains intact so
that rapid functional loading of the alveolar section
can take place and the alveolar ridge is retained.
Immediate implants can match the dimensions of
the natural roots of the teeth being replaced.
Delayed immediate implants are implantations
that take place 2 weeks to 9 months after tooth
extraction, or at least after the soft tissues have
healed, so that the implant can be covered with a
mucoperiosteal ap.
Late implant placement takes place after tooth
extraction when the alveolar bone is severely at-
rophied. As a result, in addition to the vertical and
transverse recession, the internal bone structure
also alters. Late implants are usually smaller than
the roots of the teeth being replaced.
Temporary implants are designed for short-
term use when immediate dentures need to be
anchored or when orthodontic implants (ie, mini-
implants or temporary anchorage devices) are
being used to stabilize orthodontic appliances.
Indications for Implants
Fixed implant-supported dentures have dem-
onstrated long-term reliability equal to that of
conventional xed prostheses. In the case of re-
movable prosthodontics, implant-supported res-
torations yield even better results than periodon-
tally supported partial dentures. In any event,
when treating edentulous arches, there is no al-
ternative to anchorage with implants. The general
indication for implant placement is when a remov-
able denture cannot be integrated (eg, the patient
has epilepsy) or when the patient has special oc-
cupational requirements or specic pastimes (eg,
musicians who play brass or wind instruments,
actors, or politicians). Today implant-supported
restorations are considered standard treatment
because of their long-term functional reliability
(Fig 9-4).
Uncontrolled forces may be exerted because
dentists do not perceive the intrinsic mobility of
the implant or how osseointegration results in
cushioning on loading and because periodontal
receptors are absent. This must be offset by spe-
cial shaping of the occlusal relationships.
Single-tooth implants are indicated for closing
a dental arch, for example after loss of a single
tooth within an intact arch that is free of llings or
caries. A single-tooth implant saves natural dental
tissue, for example incisors that would otherwise
have to be prepared as abutments. This key argu-
ment in favor of implant placement is supported
by the fact that a single-tooth implant usually has
a better outcome than treatment with an anterior
partial denture.
Endosseous dental implants are indicated for
small edentulous gaps, shortened dental arches,
or reduced residual dentitions with large eden-
tulous gaps and an unfavorable abutment ar-
rangement; only implant support can guarantee
the static relationships in these circumstances.
Implants are especially indicated for edentulous
arches that do not offer adequate retention for a
complete denture because of advanced resorp-
tive atrophy of the alveolar ridges or jaw defects.
General contraindications include surgical risks,
primarily in a wide variety of cardiovascular dis-
eases and other organic conditions (eg, liver
damage). Acute infections, leukemia, diabetes, and
impaired immune resistance are also contraindi-

338
Implant Terminology
cations for implant placement. In addition, im-
plant placement is ruled out in patients receiving
drug treatment for rheumatic diseases, various
skin and autoimmune diseases, AIDS, and other
acute infectious diseases (especially in the oral
cavity) as well as in patients with depression or
women who are pregnant (Fig 9-5).
If bone quality is reduced as a result of bone
disease (eg, osteoporosis) or calcium excretion is
increased in patients with renal insufciency, im-
plant placement is equally questionable, just as it
is in the case of patients who have severe physi-
cal or mental disability or personality-altering
psychopathies or who are poorly motivated and
Fig 9-4 Implants that act as a tooth root replacement are suitable for universal use. If there are no specic contraindications,
implants may be regarded as the standard treatment. This means it is possible to anchor a denture in the mouth without involving
other teeth. Combined forms of anchorage are often used; that is, a removable partial denture may be anchored on implants and
natural abutment teeth.
Indications for
dental implants
Anchoring abutments for
partial dentures to bear
prefabricated retentive
elements
Gap-supporting partial
denture abutment in large
edentulous gaps
Single-tooth implants
for closing a dental arch
Anchoring abutments in
edentulous arches for
complete dentures
Contraindications to
dental implants
General contraindications in
organic disease:
Cardiovascular disease
or liver disease
Acute illnesses: Leukemia,
diabetes, rheumatic diseases,
or autoimmune diseases
Local contraindications:
Poor bone supply, occlusal
anomaly, parafunction, or
diseases of the oral cavity
Personal contraindications:
Depression, psychopathies,
mental disability, lethargy, or
lack of motivation
Fig 9-5 Because implant placement requires considerable surgical and operational effort, a general contraindication exists if there
are surgical risks that would also make other clinical procedures difcult; chronic or acute illnesses therefore rule out any implant
placement. The patient’s personal disposition, such as poor motivation and psychopathies, may also prohibit dental implantation.

339
Implantation Methods
lethargic. A local contraindication exists if the
bone supply is too small for an implant bed; if the
vertical distances or alveolar ridges are too small
or too large; or if there are anomalies of occlusal
position, parafunctions, or a residual dentition re-
quiring remedial work.
Inammatory reactions at the marginal peri-
odontium display patterns and features similar
to inammation in the peri-implant tissue, which
means there are no appreciable differences be-
tween peri-implantitis and periodontitis despite
the different biologic structures involved. Exces-
sive stresses, which have only minimal inuence
on periodontally damaged teeth, nevertheless
have a much greater impact on peri-implant in-
ammation.
The part enclosed by tissue (ie, mucosa, bone)
as far as the gingival collar is called the endo-
structure and comprises the implant apex, im-
plant body, and implant shoulder. This part has to
divert the masticatory load into the bone. Com-
pared with the functional root surface of natural
teeth, endosseous implants have a smaller reten-
tive surface in the bone. Therefore, endosseous
implants are less able to absorb masticatory pres-
sures than natural teeth.
The exostructure is the part protruding out of
the tegument into the oral cavity, which compris-
es the neck of the implant and the abutment. This
structure is the particular hallmark of an open
implant, which pushes through the closed cover-
ing of the body and can form an entry portal for
pathogens. This structural feature is also a limit-
ing factor in terms of indications.
Implantation Methods
The various methods of implantation are differen-
tiated according to the localization of the dental
implants.
Transdental implants are sunk into the bone
through the root canal of a tooth to lengthen the
natural root (Fig 9-6). In an apically closed im-
plantation, the transxation pin is moved into the
periapical bone, whereas an apically open im-
plantation is combined with an apicoectomy. This
transdental xation system is a combination of
conventional root pins and endosseous implants.
The physiologic periodontium remains intact and
a closed implant results.
Transosseous implants are mandibular implants
that run vertically through the entire mandibular
body (Fig 9-7).
Fig 9-6 A transdental (endodontic) im-
plant is sunk into the bone through the
root canal and lengthens the natural root.
A distinction is made between apically
closed implantation, in which the trans-
xation pin is placed in the periapical
bone, and apically open implantation,
which is combined with an apicoectomy.
Fig 9-7 A transosseous (trans mandibular)
implant is placed caudally through the
mandib ular body and extends into the
tooth.

340
Implant Terminology
Intramucosal implants are ball attachments that
are sunk into the mucosa and xed basally to a re-
movable denture (Fig 9-8). The intramucosal ball
attachment is sunk into a cavity in the jaw mucosa
that is lined with normal epithelium. The button-
shaped retentive part sits rmly in the denture
base and is removed from the implant bed when
the denture is removed.
Subperiosteal implants have a custom model-
cast framework that is interposed between bone
surface and periosteum (Fig 9-9). To do this, the
bone surface is exposed and an impression is
taken. The framework is accurately prepared by
the model casting technique and placed onto
the bone surface so that it can be subsequently
re-covered with the periosteum and mucosa.
The abutments puncture the mucosa at dened
points.
Endosseous-subperiosteal implants are sunk
into the bone as well as interposed between the
bone surface and the periosteum (Fig 9-10). The
abutments break through the mucosa covering of
the dental arch. These implants are produced us-
ing the model casting method by preparing the
implant bed into the bone and taking an impres-
sion of the implant bed.
Endosseous implants are root replacement
parts that are sunk into the bone and puncture
the mucosa of the dental arch (Fig 9-11). Endos-
seous implants are placed into a form-tting cav-
ity in the jawbone, which has been prepared with
special instruments suited to the form of implant.
Fig 9-8 An intramucosal implant is the ball attachment of a
removable prosthesis that is sunk into the mucosa. The ball
attachment is sunk into an articial cavity in the mucosa of the
jaw, which is lined with normal epithelium.
Fig 9-9 A subperiosteal implant is inter-
posed as a metal framework between
the bone surface and periosteum. After
an impression of the bone surface has
been taken, the accurately tting metal
framework is prepared by the model
casting technique and placed onto the
bare bone surface.
Fig 9-10 An endosseous-subperiosteal
implant is sunk into the bone between
the bone surface and periosteum; the
abutment penetrates the mucosa of the
dental arch. It is made by the model cast-
ing method. The implant bed is prepared
into the bone.
Fig 9-11 An endosseous implant is sunk
into the bone and punctures the mucosa
of the dental arch. The part enclosed by
tissue is the endostructure, and the part
protruding into the oral cavity is the exo-
structure; the mesostructure is the com-
ponent that connects to the prosthetic
replacement.

341
Implant Integration
Implant Integration
Bone displays various tissue reactions with re-
spect to the implant material. The tissue reaction
of the implant bed can be inuenced by micro-
morphologic and macromorphologic improve-
ments in retention of the implant body, for ex-
ample special coating techniques, roughening, or
screw threads.
During implant healing, connective tissue en-
capsulation of the implant (distance osteogen-
esis) may occur, or a capillary gap may form
between bone and implant (Fig 9-12). Collagen
bers may also be deposited on the implant sur-
face (contact osteogenesis) (Fig 9-13).
Osseointegration is a direct structural bond with
no separating layer of connective tissue between
the bone tissue and the implant (Fig 9-14). This
bond forms a rigid (ankylotic) connection in which
periodontal bers are absent, and thus the im-
plant has only minimal mobility. Mobility only oc-
curs as a result of the elasticity of the surrounding
bone. The bond between implant and bone must
ensure the transfer of forces on loading of the im-
plant.
A biologic connection is created between epi-
thelial cells of the mucosa and the implant neck: A
junctional epithelium with basal lamina is formed
out of glycoproteins (Fig 9-15). This tissue junc-
tion has histologic and biochemical characteris-
tics similar to those of the junctional epithelium in
natural teeth and carries the epithelial mucosa up
to the hard surfaces of the implant. This junction-
al epithelium has a constant rate of renewal and
thus prevents bacterial deposits on its surface.
Similarly, neutrophilic granulocytes accumulate
in this area, and these are able to resist periodon-
tal or peri-implant infections. In addition, in the
tissue area—similar to the situation with natural
teeth—a system of circular connective tissue -
bers running perpendicular to the implant surface
is formed that xes the mucosa to the implant. It
has not yet been proved whether these bers are
anchored rmly to the implant surface.
Fig 9-12 (top) When connective tissue encapsu-
lation occurs or a capillary gap forms between the
bone and the implant during the course of implant
healing, this is known as distance osteogenesis.
Fig 9-13 (center) Contact osteogenesis is complete
bony (osseous) containment of an implant without
any separating layer of connective tissue.
Fig 9-14 (bottom) Ion exchange can occur if there
is close chemical ongrowth of bone onto the implant
(exchange osteogenesis). During healing, the implant
is incorporated into the physiologic metabolism of
the growing bone. This functional ankylosis is known
as osseointegration.

342
Implant Terminology
After implant healing is completed, the implant
has to be subjected to normal loading to ensure
physiologic bone maintenance because only load-
ed bone will stabilize and be stimulated to form
new tissue.
Quality of Implant Materials
Implant materials are classied into four groups:
• Autogenous materials (from the same body)
• Homologous materials (from the same species)
Heterologous materials (from a different spe-
cies)
• Alloplastic (nonbiologic) materials
Autogenous implants are derived from the
same organism, for example extracted teeth or
endogenous bone grafts. Homologous implants
are tissue parts transferred from other people.
Heterologous implants are tissue parts trans-
ferred from a different species. Alloplastic materi-
als are metals and their alloys, ceramics, or plas-
tics. The requirements for implant materials are
mechanical stability and biocompatibility.
The mechanical properties of implant materials
and bone must be approximated to each other so
that masticatory forces do not give rise to shear-
ing stresses between bone and implant bond. The
aim is to nd a material with sufcient strength
and a modulus of elasticity matched to that of
bone. Metals have sufcient strength, elongation
at fracture, and variable elasticity, while ceramic
has high fracture toughness.
Implant material is biocompatible if the cells
in contact with the implant can participate un-
impeded in the natural process of metabolism.
Tissue that is in contact with nonbiocompatible
materials may display antibody reactions, aller-
gies, encapsulation, and toxic and inammatory
reactions and ultimately die. On the other hand,
the implant material may corrode in the body, or
it may be leached out, abraded, or resorbed.
In dental implantology, alloplastic materials are
used almost exclusively because their availability
is virtually unlimited, they are easy to store, and
they can be produced to a dened and controlla-
ble quality level. However, foreign-body reactions
to alloplastic materials may occur. In particular,
metallic implants may have complex interactions
with the implant bed tissue, resulting in corrosion
and development of metallosis in the implant bed
tissue. Metallosis can lead to a connective tissue
separating layer between bone tissue and metal
implant.
Corrosion is damage to metals or alloys caused
by chemical or electrochemical reactions. Tissue
uids and saliva, in which ions and salts are dis-
solved, act as electrolyte solutions in the body
that attack the metal. Galvanic processes between
the metallic materials of the implant and super-
structure, contact and friction corrosion, as well
as local elements may give rise to other damage
to the implant and the tissue of the implant bed.
The movements of ions in tissue disrupt the
natural physiologic processes, can disturb the
biologic equilibrium in cell growth, or can trig-
ger allergies. Metal ions also get into the diges-
tive tract via saliva and reach organs of the body
where they accumulate beyond the physiological-
Fig 9-15 An epithelial join between the mucosa and the im-
plant surface is formed on the smooth or polished neck of
the implant. Junctional epithelium is formed with a basement
membrane that displays similar characteristics to marginal peri-
odontium. A buildup of leukocytes may also be noted in this
tissue area. At the crestal transition (passage through the al-
veolar bone), modern implants have special surface structures
that can improve attachment in the hard cortical layer.

343
Implant Material and Tissue Reaction
ly tolerated limit. The transport of ions can dam-
age remote organs.
Metals can protect themselves against various
forms of corrosion by means of a passivating
surface layer. Many metals spontaneously form
a passivating protective layer by oxidation; these
metals are passivatable. An oxide lm is formed
over the entire metal surface, which prevents the
exchange of charge carriers with other media and
protects the metal against further corrosion. This
passivation layer can be mechanically damaged
but regenerates quickly by renewed passivation.
Some base metals form stable, highly noble
surface oxides as a passivation layer even when
the oxygen supply is minimal. Titanium and its
alloys display particularly rapid growth of a pas-
sivation layer; other implant alloys contain pas-
sivating additives. Gold and platinum alloys, as
precious metals, are corrosion resistant even
without a passivating protective layer.
Saliva forms a closed electrical circuit between
jawbone and implant, where local galvanic cur-
rents transport the corrosion products. The depo-
sition of corrosion products rst causes dark dis-
coloration in the implant bed tissue; cell activity is
impeded, and aseptic necrosis may ensue. These
reactions do not occur with titanium. Ceramics
and plastics are corrosion resistant but can be re-
sorbed by bodily uids.
Implant Material and
Tissue Reaction
Dental implants have to fulll extremely varied
requirements because they protrude into the oral
cavity and are in contact with various types of tis-
sue, such as jawbone, periodontium, and gingiva.
They are made almost exclusively of alloplastic
material, such as metals, ceramics, and compos-
ites (Fig 9-16). The mechanically stable metallic
materials include titanium and titanium alloys.
In terms of nonmetallic implant materials, acryl-
ics, aluminum oxide ceramics, biolite carbon,
glass-ceramics, calcium phosphate ceramics, and
hydroxyapatite ceramics have been tried and, in
most cases, rejected.
Composite materials are the coatings applied
to implant surfaces, for example titanium plasma,
hydroxyapatite, or biolite carbons, to achieve di-
rect ongrowth of bone onto the implant.
Alloplastic implant materials can be classied
as biotolerated, bioinert, or bioreactive, depend-
ing on their suitability for achieving intensive
osseointegration and thus according to their de-
gree of biocompatibility. Biotolerated materials
(mostly metals) form a separating layer of con-
nective tissue between the implant and its bony
Biotolerated for
distance osteogenesis:
Nonprecious alloys
(gold titanium)
Bioinert for
contact osteogenesis:
Aluminum and
zirconia-ceramic
Bioreactive for
ongrowth of bone:
Hydroxyapatites and
calcium phosphate
bioglasses
Composite materials
Fig 9-16 Dental implants are almost exclusively made
from alloplastic (nonbiologic) materials. Metals have the
most favorable physical properties, such as hardness, tough-
ness, fracture strength, and elasticity; among metals, only
pure titanium is sufciently biocompatible. Materials are
classied as biotolerated, bioinert, or bioactive, depend-
ing on their degree of biocompatibility.

344
Implant Terminology
bed, a process known as distance osteogenesis.
The interlayer of connective tissue weakens the
retention of the implant and may arise because
of the interaction of bone with toxic metal ions
or when the implant is loaded during the healing
phase. Bioinert materials (mostly oxide ceramics)
hardly release any ions and do not react with the
tissue of the implant bed. The bone attaches di-
rectly to the implant material, which is known as
contact osteogenesis. Bone regeneration extends
right up to the implant surface. Bioreactive ma-
terials (mostly hydroxyapatites, tricalcium phos-
phate) actively create close chemical ongrowth of
bone. Calcium phosphate ions are released from
the apatite portion of these materials, and these
ions become involved in the physiologic metabo-
lism of the growing bone during healing of the
implant. Bone is deposited in the surface pores
of the implant without an interlayer of connective
tissue. Faster osseointegration may ensue.
Osseointegration refers to the rigid (ankylotic)
join between implant and bone, which is evident
as a direct transition from bone to implant with-
out an intermediate layer of connective tissue. Ion
exchange between implant and bone (exchange
osteogenesis) occurs in this functional join; the
implant appears to be incorporated into the phys-
iologic metabolism of the growing bone.
The mechanical roughness of the implant sur-
face in its micromorphology is vitally important.
This is because the macroscopic mechanical re-
tentions of the bone-to-implant contact ensure
primary stability during the healing phase. The
biologic reaction of active bone growth results in
mechanical xation in microscopically small un-
dercuts when the bone grows into surface pores.
Surface roughness with a depth of 1.4 µm cre-
ates stable bioadhesion of the implant in the im-
plant bed. It is impossible to ascertain exactly
what inuence the chemical composition of the
implant coating has on the stability of the bone-
to-implant connection. However, the proven suc-
cess rate of over 95% of implants without articial
overlying mineral or protein seems to indicate
the functionality of a roughened surface without
a coating. To achieve this, healing must take place
in an absolutely immobile state because this is
the only way bone can grow onto the implant
surface. If there is any mechanical loading, bone
contact is lost and separating layers of connec-
tive tissue will form.
As a result of this roughness, the surface is
more wettable, and bone contact is markedly im-
proved. The rough surface also prevents the for-
mation of intermediate layers of connective tis-
sue, increases the formation of new bone, and
enhances the bioadhesion of the bond between
implant and bone.
The elastic behavior of implant and bone de-
termines the functional integration of the implant
into its bony surroundings. The greater the con-
gruence of the elasticity moduli, the better the in-
growth of the implant, and the formation of new
bone will also be stimulated. The elasticity of tita-
nium can be perfectly adapted to the bony bed.
Titanium as an Implant
Material
Titanium is currently the most widely used im-
plant material because of its mechanical and bio-
compatible properties. The mechanical character-
istics of pure titanium, expressed in a 0.2% yield
strength and modulus of elasticity, vary widely
depending on the admixture of iron and oxy-
gen. Titanium surfaces bind oxygen within frac-
tions of a second and release iron equally well;
different strength values arise, depending on the
amount of the admixtures. The yield strength and
modulus of elasticity also increase as a result of
the strain hardening after cold deformation. This
effect is given as a grade, whereby the greatest
hardening of pure titanium reached upon cold de-
formation is grade 4.
An increase in the mechanical values is achieved
by forming alloys with aluminum and niobium (or
vanadium). Both additives partly prevent the trans-
formation from the body-centered high-temperature
phase to the hexagonal low-temperature lattice,
so that a crystal mixture from both phases exists.
This two-phase crystal mixture is known as
(αβ)-titanium and displays lattice stresses that
are reected in a marked increase in these values.
However, biocompatibility seems to suffer in the
process.
The excellent biocompatibility of pure titanium
is due to its passivatable surface. Pure titanium is
an extremely ignoble metal in the electrochemical
series and spontaneously forms a passivating ox-

345
Titanium as an Implant Material
ide on the surface, which displays bioinert behav-
ior in tissue. The passivated titanium surface does
not corrode, and only a few titanium ions get into
the surrounding bone. Titanium ions do not ap-
pear to prevent bone apposition. Titanium with its
various compounds is in any case a natural con-
stituent of the body, and as yet reports of allergic
reactions to titanium have been extremely rare,
with an estimated prevalence of 0.6%. Therefore,
titanium should preferably be used non-alloyed
because alloy constituents may release ions due
to corrosion.
Pure titanium has become almost fully estab-
lished as an implant material, its excellent bio-
compatibility and the roughening of the surface
being crucial prerequisites to osseointegration.
Pure titanium can be planed to a very smooth n-
ish by machining of the surface, leading to good
epithelial attachment in the emergence area and
facilitating excellent cleaning. However, distance
osteogenesis with poor quality of anchorage aris-
es in the implant bed.
Various methods are used to roughen the implant
surfaces, such as acid etching, airborne-particle
abrasion, anodic oxidation, and application of
coatings. In the acid-etch technique, the surface
processing is done with various combined acids
that roughen the titanium surface in the microm-
eter range (approximately 1 µm). The osteoblasts
are able to embed in this rough surface, resulting
in improved bone apposition. Surface machining
by airborne-particle abrasion with abrasives, such
as aluminum grit size 1.2 to 2.2 µm, produces
medium roughness of 1.4-µm depth, which is
the most advantageous roughness for contact
osteogenesis. As blast particles may remain in
the surface depending on the blasting medium,
the abraded surfaces are then acid etched to pro-
duce an even ner surface relief. A further etching
process with isotonic sodium chloride solution
alters the wettability so that bone apposition is
accelerated (Fig 9-17). If the implant is also treat-
ed with ultraviolet C radiation after the combined
etching processes, the surface tension is switched
Fig 9-17 Smooth titanium surfaces are hydrophobic (ie, they repel water). Faster osseointegration can be achieved by hydrophilic,
osteoinductive properties, as in the case of the SLActive implant surface from Straumann. The surfaces interact with the tissue and
accelerate cell activity so that growth-promoting cytokines (bone morphogenetic proteins) are released. In the SLA production
process, the implant surfaces are airborne-particle abraded with large-grit particles followed by acid etching with heated hydrochlo-
ric and sulfuric acid. The acid etching produces a microroughness of 2 to 4 µm. The surface is subsequently conditioned in nitrogen
and stored in an isotonic salt solution. Bone contact with the conditioned implant surface is considerably improved, which shortens
the healing process to about 3 to 4 weeks and speeds up osseointegration. Immediately after implant insertion, substantially more
bone is formed on the enlarged SLActive surface; in special cases, there is an increase in bony tissue. (Illustration courtesy of Straumann.)

346
Implant Terminology
from negative to positive, the osteoblast reaction
increases, and more intensive bone-to-implant
contact results.
Surface coating by anodic oxidation (anodizing)
is performed by means of spark discharge in an
aqueous electrolyte where calcium phosphates
are amorphously integrated (Fig 9-18). Accelerat-
ed bone regeneration and more intensive osseo-
integration occur at the porous implant surface.
Surface coating with hydroxyapatites is done by
sintering in an immersion bath. The chemical de-
position of nanoparticles is intended to produce
fast osseointegration with high bone-to-implant
contact.
The implant surface can be conditioned and
enlarged sixfold by coating with titanium plasma
(Fig 9-19). This method involves welding particles
of titanium powder onto the titanium in a layer 30
to 40 µm thick at high temperature; this produces
a dened roughness of 1.5 µm.
Zirconia ceramic is a polycrystalline material that
exists in three chemical phases with different prop-
erties: monoclinic, tetragonal, and cubic. The tetra-
gonal phase, which is suitable as an implant ma-
terial, is metastable at room temperature and can
be destroyed by thermal stress (friction heat dur-
ing grinding). Zirconia is biocompatible and can
be radiographically depicted like metal. It has
Calcium phosphate layer
Protein structures
Bone substance
Titanium
Titanium oxide
Fig 9-18 (top) Surface conditioning
of titanium implants by electrochemi-
cal anodizing produces an oxide layer
of 15 to 20 µm into which 40% calcium
phosphates are amorphously integrat-
ed under spark discharge. (Illustration
courtesy of ZL Microdent.)
Fig 9-19 (bottom) The physically measurable surface can be enlarged sixfold by means of plasma coating. The resulting roughness
of 1.4-µm depth improves osseointegration of the implant. Given the concentration of calcium phosphates in the implant surface,
proteins should be better absorbed and healing of the bone wound promoted. Faster healing of the implant has not been observed
with coated implants.

347
Forms of Endosseous Implants
high strength, is extremely break resistant, can be
stained to natural tooth color, and is superior to
titanium in terms of esthetics and plaque resistance.
Aluminum oxide ceramics are chemically, ther-
mally, and mechanically highly resistant and dif-
fer considerably from bone in terms of elasticity,
so shearing forces arise in the bone-to-implant
bond during loading. The aluminum oxide sur-
face behaves in a bioinert fashion, which means
the bone structure is densely deposited.
Calcium phosphate ceramics are bioactive ma-
terials comprising calcium oxide and diphospho-
rus pentoxide; they are similar to mineral bone.
Hydroxyapatite ceramic and tricalcium phosphate
ceramic are of clinical relevance.
Forms of Endosseous
Implants
Endosseous implants are open implants that pro-
trude out of the body’s surface. They are dictated
by the anatomical conditions, such as shape and
position of the maxillary sinus and the mandibular
canal. Following are different types of implants:
• Cylinder implants
• Hollow-cylinder implants
• Screw implants
• Blade implants
• Abutment-and-pin implants
• Needle implants
Cylinder implants (or cylindric implants) are
full-body implants whose surfaces are rough-
ened by chemical or mechanical processing or by
a plasma coating (Fig 9-20). As a result, the sur-
face is enlarged and bond stability is increased.
Some cylinder implants have apical perforations,
which ll with bone during the loading-free heal-
ing phase to achieve additional stabilization. For
cylinder implants, system-specic bone cutters
must be used to prepare a form-t implant bed.
The implant can be tapped into the cavity with
a seating instrument until it wedges in the can-
cellous bone in a press t. Intramobile cylinder
implants (eg, IMZ implant system) comprise the
implant body and a cushioning component, the
intramobile connector.
A hollow-cylinder implant comprises a rotation-
ally symmetric, perforated implant body that has
a large implant anchorage area and, because of
its small implant volume, requires only minimal
loss of bone substance when preparing the im-
plant bed (Fig 9-21). The implant bed is cut with a
hollow cutter at low speed, which is intended to
produce a form-t implant bed with uniform pres-
sure distribution to the bony tissue. Various types
of hollow-cylinder implants are available (eg, ITI
hollow-cylinder implants, Straumann) as single
cylinders and double cylinders, which support the
abutment on a connecting bar. Hollow cylinders
have an implant stiffness that is similar to bone,
which reduces the stresses between bone and im-
plant when the bone grows into the perforations.
Screw-type implants have a cylindric or tapered
implant body with screw threads (Fig 9-22). The
surface of metallic screw implants (mostly titani-
um) can be coated. Self-tapping threads are distin-
guished from those that are screwed into precut
cavities. The thread anks are intended to guaran-
tee uniform transfer of force into the bone with-
out stress peaks. Self-tapping threads sit rmly in
the loose cancellous bone and are immediately
loaded. On precutting of threads, contact surfaces
for the implant may break off, but the bone chips
are ushed out before the implant is screwed in
place, thus guaranteeing better healing. Tapered
screw implants have an approximate root shape
so that little bone tissue has to be sacriced for
immediate implant placement.
Blade implants are extension implants with
greatly expanded, at, disk-shaped, or even
double-blade–shaped implant bodies (Fig 9-23).
Extension implants offer large, functionally ef-
fective surfaces for bone apposition. The forms
of implant commonly used today emerged from
extension implants. Blade implants may be indi-
cated where there is an extreme horizontal lack
of bone and when a rotationally symmetric im-
plant cannot be inserted. The drawback to blade
implants lies in the high bone loss if explantation
is required. This is because the implant needs to
be widely exposed if it has to be removed.
Abutment-pin implants are endosseous implants
that have a pinlike implant shaft and abutment-
like wing extensions for antirotation protection
(Fig 9-24). The slender aluminum oxide ceramic
pins were once used as a late implant for single-
tooth restoration in the maxillary and mandibular

348
Implant Terminology
anterior region. These delicate tooth root replace-
ments are no longer used because of the risk of
fracture.
Needle implants are long, needle-shaped metal
pins made of tantalum (Fig 9-25). The surface-
ground pointed needles were either self-drilling
and driven into the bone with hammer blows or
self-tapping and inserted with a contra-angle.
Several needles were always inserted, for exam-
ple three crossing needles or seven to ten needles
as a needle path. Needle-shaped implants are no
longer used because of the high failure rates.
Fig 9-20 Surfaces of whole-cylinder
implants may be roughened by chemical
or mechanical processing or by plasma
coating, which displays bond stability.
Some cylinder implants have apical per-
forations.
Fig 9-21 Hollow-cylinder implants are
perforated tubes with a double bonding
surface. Only a little bone tissue is milled
out to prepare the implant bed.
Fig 9-22 Screw-type implants with a
cylindric or tapered implant body are cre-
ated with threads that evenly transfer
force via the thread anks. The surfaces
can be coated. Screw implants may have
self-tapping threads.
Fig 9-23 Blade implants are extension
implants with a double-blade shape and
a at body that provide functionally effec-
tive surfaces for bone apposition. They
are only indicated where there is an ex-
treme horizontal lack of bone.
Fig 9-24 Abutment-pin implants, which
are no longer used today, were pin-type
endosseous implants with abutment-
type wing extensions for antirotation pro-
tection. They were made from aluminum
oxide ceramic and were not very fracture
resistant.
Fig 9-25 Needle implants, which are
no longer used today, were made from
tantalum with surface-ground points that
were driven into the bone with hammer
blows. Several needles were always in-
serted.

349
Design of Endosseous (Permucosal) Implants
Design of Endosseous
(Permucosal) Implants
The parts of an implant are individually function-
ing or morphologically distinct sections, such as
the implant apex, implant body, implant shoul-
der, implant neck, and abutment (Figs 9-26 and
9-27). The implant body is the part of a root re-
placement sunk into the bone (endosseous), in
which the implant shoulder and implant apex can
be differentiated. The two types are hollow-body
and full-body implants. Hollow-body implants are
perforated, hollow cylinders (ITI hollow-cylinder
implants) with an internal and external implant
anchoring surface, a smaller implant volume, and
a deformation behavior similar to that of bone.
Full-body implants are cylindric or tapered and
enable osseointegration at the external surface
as bone is able to grow into a basal perforation
in the implant and stabilizes the implant against
torsion.
Implant body
Implant neck
Implant shoulder
Implant apex
Implant abutment
Superstructure/
tertiary component
Exostructure/
secondary component
Connecting screw/
mesostructure
Endostructure/
primary component
Fig 9-26 Structural components of an implant.
Fig 9-27 The implant bed is the bone cavity for the implant
body; it must be rigorously prepared and must not harm inter-
nal bone structures, such as the mandibular canal in the man-
dibular body, as shown here.

350
Implant Terminology
The implant apex is the lower (apical) portion
of the implant body, by means of which the force
directed vertically onto the implant is transferred
to the bone. In screw implants, part of the verti-
cal force is directed into the bone via the screw
threads.
The implant shoulder forms the transition from
implant body to implant neck or to the abut-
ment elements. This protruding initial part of the
implant body is sunk in the bone and lies in the
area where the compact bone is penetrated. The
implant shoulder is narrow, high-gloss polished,
and beveled buccally to allow esthetically advan-
tageous shaping of the replacement tooth.
The implant neck lies in the area where the mu-
cosa is penetrated, between the implant body
inserted in the jawbone and the abutment. The
coronal part of the implant body is sometimes
known as the implant head. The implant neck is
particularly pronounced in one-piece implants and
lies slightly supragingivally so that the implant
shoulder lies markedly above the alveolar ridge.
The implant neck is an inverted cone or is slightly
collar-like to protect the peri-implant transition
against vertically directed stresses. It is polished
to a high gloss to prevent plaque from being de-
posited. The mucosal collar should attach without
irritation to a smooth, rounded implant neck.
A junctional epithelium, an epithelial adhesion,
and a brous system for attachment of the mu-
cosal collar may be formed. To adapt the height
of the implant neck to the mucosal thickness, ex-
changeable spacer sleeves can be tted. These
spacer sleeves can be replaced by new, high-
gloss polished components if they become badly
contaminated or damaged.
The implant post, also known as the abutment,
is the buildup protruding into the oral cavity; it
sits on the implant neck and directly receives the
superstructure or a special mesostructure. In one-
piece implants, the abutment is rmly joined to
the implant body, whereas in two-piece implants,
the implant body and the abutment are separated
and joined together by a separate screw connec-
tion (Fig 9-28). The implant body is generally re-
ferred to as the implant for short.
The connection between implant neck and abut-
ment must ensure anti-rotation protection, free-
dom from gaps, and adequate mechanical stabil-
ity (Fig 9-29). Abutments can be cemented into,
screwed into or onto, or force tted onto the im-
plant body, and they are then rigidly joined to-
gether.
An intramobile element made of plastic can
also be inserted between implant and super-
structure (Fig 9-30). This intramobile element is
Fig 9-28 A distinction is made between
one-piece and two-piece implants. One-
piece titanium implants with a very small
diameter are usually intended for tem-
porary use as provisional implants. Two-
piece implants consist of the implant
body and the abutment.
Fig 9-29 The quality of the connection
between implant body and abutment
affects the security of the abutment
against tilting and rotation. A distinction
is made between internal and external
connections.

351
Implant-Abutment Connection
exible and is intended to imitate the resilience
of the periodontium when a denture with mixed
support (seated on implants and natural teeth) is
being fabricated.
The superstructure is the prosthetic replace-
ment, which can be cemented onto the abutment
in a removable or xed fashion, bonded, or screwed
in a partly removable way. A ready-made cylinder
can be inserted between superstructure and
abutment; it can take the form of a prefabricated
bondable or screwable titanium or gold cylinder,
ceramic coping, or burnout plastic cylinder.
The implant disk in two-piece implants is an
abutment in the form of a circular ledge on the
implant body that ends with the superstructure
and ensures an optimal marginal t.
Implant-Abutment
Connection
In two-piece implants, the form and stability of
the connection between implant and abutment
needs to be examined in more detail. For pros-
thodontic use, it is essential to clarify what antiro-
tation protection exists, whether the connection
is tapered or parallel, and whether an external or
internal connection exists.
Antirotation or anti-tilting protection refers to
the connection being secured against torque in
the vertical connection axis, which is especially
important in single-tooth restorations. Several
implants that are rigidly connected (splinted) by a
partial denture or denture framework are not sub-
ject to rotation. In these circumstances, non-axial
forces can tilt the implant-abutment connection,
which can lead to loosening of the implant screw.
Antirotation protection must exist with internal
and external connections and can be created by a
suitably angled connection prole (eg, internal or
external hex) (Fig 9-31).
Tapered or parallel contact surfaces in the
implant-abutment connection affect the reliabil-
ity of the connection. The inclination of the con-
tact surfaces varies from parallel-walled to conic-
ity and from 1.5 to 11 degrees. Very steep-walled
conical connections develop very high surface
pressure in the contact area so that permanent
conical connections can arise as a result of cold
welding.
External and internal implant-abutment connec-
tions can loosen or break due to minimal loading
movements. Comparatively speaking, internal con-
nections prove more stable than external connec-
tions, but a long internal connection will weaken
the implant body so that a fracture could occur
there. If several implants are inserted to support a
long-span partial denture, an external connection
Fig 9-30 Structural components of an
implant with an intramobile cushioning
component.
Superstructure
Intramobile cushioning
component
Tertiary screw
Titanium insert
(carries the
cushioning component)
Implant body
(coated, perforated
cylinder implant)

352
Implant Terminology
in the case of divergent implant axes offers the
advantage that the partial denture can be screwed
directly in place. With internal connections to
nonparallel implant axes, the abutments have to
be parallelized for a common path of insertion.
External connections can be shaped in the form
of an external hex (Fig 9-32). The implant as a full
screw bears a low, parallel-walled external hex
ring above the implant shoulder, through which
the retention screw is guided. The connection is
rotationally stable but might tilt as a result of non-
axial forces, which may loosen the screw mecha-
nism and lead to fracture of the connection (eg,
Brånemark implant, ZL Microdent implant).
Implant systems with internal anchorage have
one path of insertion, which results from the im-
plant axis. Where there are several implants, the
variations in the path of insertion must be bal-
anced by the abutments in order to receive splint-
ed structures. The abutments can either be par-
allelized or angled toward the implant axis (Fig
9-33).
Internal connections with a parallel-walled tube-
in-tube connection are rotationally stable if they
have several internal grooves for a form-t con-
nection (eg, Camlog implant). Internal connections,
in which the tapered area is octagonally or hex-
agonally shaped, are just as rotationally secure as
tapered internal connections with an additional
hex (eg, Straumann implant). Internal tapered
connections without additional antirotation pro-
tection allow for 360-degree universal positioning
of the abutment. Rotational stability is achieved
with a steep tapered connection (1.5-degree ta-
per). This type of connection is suitable for par-
ticularly short implant bodies at least 5 mm long
(Figs 9-34 and 9-35).
One-piece implants are predominantly zirconia
ceramic implants and implants with very small
diameters or temporary titanium implants. The
implant body and the abutment form a unit and
are therefore not submerged during healing.
One-piece implants with a very small diameter
(1.8 mm) have a spherical abutment for anchoring
overdentures. They can be inserted by minimally
invasive surgical techniques and can be immedi-
ately loaded.
Fig 9-31 The abutment is placed into
or onto the connection prole and xed
with a screw. The stability of this connec-
tion depends on screw diameter and the
anti-tilting protection.
Fig 9-32 An external connection be-
tween the implant parts can be rendered
rotationally secure by an angled connec-
tion prole, for example a hexagonal pro-
le.

353
Implant-Superstructure Connection
Temporary implants have a diameter around 2
mm and are used during postextraction healing
or after placement of nal implants; osseointe-
gration is not the goal.
Zirconia ceramic implants come in a variety of
forms and can be individualized by preparation.
The impression is taken in the same way as for a
normal tooth preparation.
Implant-Superstructure
Connection
Superstructures can be screwed onto an abut-
ment or a bar or, like conventional restorations,
can be cemented onto individual cementation
abutments of the implants that have been insert-
ed (Fig 9-36). Single-tooth restorations can also
be placed onto ceramic abutments by the acid-
etch technique with composites.
Screw ttings can be guided occlusally and
transversally and are used for partly removable
superstructures. Ease of removability makes re-
pairs and hygiene measures easier and is essen-
tial for long-span partly removable partial den-
tures. Screws are used for xing onto individual
abutments and onto bars. The occlusal or trans-
verse screw xation of implant-borne super-
structures is being used less and less frequently
because minor inaccuracies in fabrication cannot
be tolerated—especially on long-span partial
dentures—and it might not be possible to use a
partial denture that ts onto the model (Fig 9-37).
Occlusal screw connections must be covered
after insertion and exposed again before undoing
the screw connection. They have poor esthetics
and in some circumstances may impair mastica-
tory function.
Fig 9-33 An internal connection can be shaped to have
parallel walls or to be tapered and rendered rotationally
secure by means of various internal grooves. In addition
to an internal hex, three to eight grooves can be created.
The more grooves, the more ways the abutment can be
positioned. Universal positioning options offer a rotation-
ally symmetric connection without additional antirotation
protection.
Fig 9-34 In extremely short im-
plants, the internal connection
takes up the entire 5-mm-long
implant body, while rotational
stability arises from a steep-
walled (approximately 1.5-degree)
tapered connection in which the
sides of the cone can fuse.
Fig 9-35 The connection pro-
le of an internal cone offers no
primary antirotation protection.
The two parts of the implant are
created by an additional screw
connection.

354
Implant Terminology
Transverse screw connections are not as prob-
lematic esthetically and functionally; the tension-
free seating is easier to produce, but they do
result in large gaps that cause taste and odor
problems. They are difcult to handle and require
a voluminous, orally prominent construction with
an unsightly screw hole.
Cementation is being used more and more of-
ten because it can compensate for all the draw-
backs of screw connections (Fig 9-38). Cementa-
tion has the following advantages:
Cemented superstructures do not have the
same esthetic and functional limitations as oc-
clusal screw connections, and occlusal surfaces
do not have to be perforated for a screw.
A superstructure can be removed again if tem-
porary cements are used.
The cement layer compensates for inaccuracies
of t caused by fabrication and ensures tension-
free seating of a partial denture structure.
Different implant axes can be better compen-
sated for.
Cemented, implant-supported single crowns do
not differ from natural teeth in terms of wearing
comfort, cleanability, and amount of aftercare.
Use of customized abutments is possible so
that the path of insertion, gingival contour, and
position of the crown margin can be perfectly
shaped.
Fig 9-37 Screw connections guided occlusally are functionally
critical and will not tolerate t errors; even minor fabrication
errors might make it impossible to insert the screw tting. The
screw hole must be covered occlusally, which may be an es-
thetic drawback.
Fig 9-36 Superstructures can be screwed onto the abutment.
The screw connection can be attached occlusally or transver-
sally. Transverse screw connections are guided from the me-
siolingual direction for esthetic reasons; they allow tension-
free seating but are difcult to handle and create gaps that can
cause odor problems.
Fig 9-38 Transverse or occlusal screw connections of super-
structures are only rarely used because of the described de-
ciencies (minimal fabrication tolerance, esthetic shortcomings,
and difculty in handling). Cementing the superstructure onto
the abutment can compensate for all the disadvantages: Both
t errors and gaps are offset by the cement layer.

355
Special Forms of Implants
The disadvantage of denitive cementation is
that the superstructure cannot be removed with-
out being destroyed; that is, if the screw connec-
tion between implant and abutment breaks, the
superstructure has to be replaced. Therefore, a
rotationally stable, reliable, and loadable implant-
abutment connection is essential.
When prosthetically restoring alveolar ridge
defects that cannot be remedied surgically by
bone augmentation, a removable construction
must be used for optimum oral hygiene. Double
crowns or a bar construction can be cemented
permanently onto the abutments, while the re-
placement covering the mucosa and designed as
a partly removable restoration can be screwed
onto the substructure. A partial denture structure
with alveolar ridge replacement made of ceram-
ic can also be permanently cemented in place if
cleanability is guaranteed.
Implants can be joined together rigidly by the
superstructure or splinted. The implant-borne
restoration then distributes all stresses to the
splinted implants and reduces the loading. As in
conventional prostheses, a distinction is made
between primary splinting by xed structures and
secondary splinting by removable structures. The
more implants are included in the splinting and
the larger the supporting polygon, the smaller the
loading on the individual implant.
Concepts of occlusion for implant-supported
restorations do not differ from the concepts of
conventional prosthetics. Canine guidance or
tooth-group guidance can take place as much as
with periodontally supported dentures. Unilateral
or bilateral balanced occlusion can be construct-
ed in quasi-complete dentures that are anchored
with implants, depending on the quality of the
denture-bearing mucosa.
Special Forms of Implants
Immediate implants are conical tooth replace-
ment parts that are inserted immediately after
extraction of a tooth to shorten the edentulous
period. Immediate implant placement takes place
right away or a few days after a dental extraction
when no bone loss has yet taken place. An ap-
proximate form t between implant and socket
can be achieved by root-analog, tapered screw
implants. Implant screws with a large-volume
screw core can lie fully up against the alveolar
bone for an optimal implant-bone connection.
Immediate implant placement can only be per-
formed if the socket or extraction wound is not
infected and there are no apical defects. Imme-
diate implant placement is usually necessary if
traumatic tooth loss occurs because of an acci-
dent or if the tooth can no longer be preserved
after a tooth fracture (Figs 9-39 to 9-44).
Delayed implant placement refers to implant
insertion that takes place after epithelial wound
healing is completed, about 6 to 8 weeks after
extraction of the tooth. At that stage the socket
is grown through with connective tissue without
fully developed new bone.
Interim implants are implants with an ultrasmall
diameter (2 mm) with which immediate partial
dentures are anchored during the healing phase
of the denitive abutments. Complete or partial
dentures can be supported on such temporary
implants to accomplish the following:
Protect denitive implants against unwanted
stresses during the healing period
Facilitate guided bone regeneration in preim-
plant augmentation or sinus elevation proce-
dures
Allow a temporary immediate restoration be-
fore delayed implant placement
• Fix orthodontic appliances (mini-implants)
Fix the drill template for denitive implant place-
ment
For transitional implants, a pilot hole is placed
in the bone with a spiral drill, and the interim
implant is screwed in place. These implants are
loaded immediately after placement and removed
again after the interim denture–wearing period.
Mini-implants
Special endosseous palatal implants or mini bone
screws are known as mini-implants; they provide
positionally stable xation and can be used for
stationary anchorage of orthodontic appliances
(Fig 9-45). Orthodontic stresses on anchoring
teeth to which the appliances would otherwise
be xed can thereby be avoided. Other anchoring
methods, such as headgear or maxillomandibu-
lar elastics, are not necessary, which reduces the

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Implant Terminology335The term implant refers to a material introduced into the body to replace or reinforce an organ or tissue, such as bone chips or endoprostheses (eg, arti cial blood vessels and joint replacements). Thus, in dentistry the term implantology refers to the placement of dental implants (parts to replace tooth roots) in the maxilla and mandible to receive tooth replacements. These tooth root replacement parts are implanted from alloplastic (foreign to the body) materials into the jaw area to anchor individual teeth or an exten-sive  xed or removable prosthesis.Closed implants are surrounded on all sides by the body’s own tissues, for example closed magnetic implants, joint replacements, or heart valves. Open implants are tissue replacement components sunk into the body that permanently protrude through the surface of the body and can form a constant entry portal for germs. The root replacement parts commonly used in dentistry for af xing dentures are open implants (Fig 9-1).Implant placement takes place in several stages, starting with history taking, clinical examination, and radiographs and concluding with the actual surgical procedure. De-pending on the timing, a distinction can be made between one-stage (single-phase or one-step) and two-stage (dual-phase or two-step) implant placement.In one-stage implant placement, the implant is inserted so that the exostructure (im-plant post/abutment) protrudes through the mucosa during the healing phase and is functionally loaded by an implant-supported denture immediately after implantation. No prosthetic replacement is worn for about 2 weeks to ensure that wound healing of the mucosa is not impeded. In one-stage implantation, one-piece implants are used, and these can be applied in an edentulous mandible for bar-retained prostheses and  tted in a single session. 336Implant TerminologyFig 9-1 Open implants are replacement tissue parts sunk into the body with an implant component permanently protruding through the surface of the body. This provides a constant entry portal to the inside of the body for disease pathogens. Dental root replacement parts for xation of dentures are open im-plants. Closed implants are surrounded on all sides by bodily tissues, for example closed magnetic implants, replacement joints, or heart valves. These implants cannot be corroded by external factors and do not offer any entry portals for patho-gens.SuperstructureImplant bodyAlveolar boneGingivaImplant abutmentFixation screwImplant bedFig 9-2 An endosseous implant comprises the endostructure (the part sunk into the bone, or implant body) and the exo-structure (the part protruding out of the tissue), onto which the mesostructure (the component that connects to the prosthetic replacement) is xed.Fig 9-3 The abutment is intended to connect the implant to the superstructure (that is, the tooth replacement). Ball attach-ments can be used for removable complete dentures, such as those also tted onto root crowns. 337Indications for ImplantsIn two-stage implant placement, the implant is covered by sutured mucosa and is not function-ally loaded by a tooth replacement throughout an unloaded healing phase (about 3 to 6 months) when direct bony ingrowth (osseointegration) of the implant is possible. In a second procedure, the neck of the implant is exposed and the meso-structure (abutment) is screwed in place. Two-part implants, in which the endostructure (implant body) and exostructure (abutment) are separate (Fig 9-2), are available for this two-stage method. In two-part implants, the abutment can be aligned with the prosthetic replacement (Fig 9-3).The implant bed is the bony cavity for endosse-ous implants; in the case of mucosal implants, it is the dimensionally accurate hollow in the muco-sa into which the implant is inserted. A cavity con-gruent with the implant is milled into the bone or punched into the mucosa. Internally cooled im-plant cutters are available for preparation of the bony implant bed. These are special bone cutters for low-speed milling (approximately 200 rpm). They have a central hole in the cutter shaft for the coolant, which cools the cutter and the prepara-tion eld while simultaneously and continuously rinsing out the bone chips.Immediate implant placement refers to implan-tations that are performed directly after tooth ex-traction and before bony consolidation of the sock-et. The alveolar bone contour remains intact so that rapid functional loading of the alveolar section can take place and the alveolar ridge is retained. Immediate implants can match the dimensions of the natural roots of the teeth being replaced.Delayed immediate implants are implantations that take place 2 weeks to 9 months after tooth extraction, or at least after the soft tissues have healed, so that the implant can be covered with a mucoperiosteal ap.Late implant placement takes place after tooth extraction when the alveolar bone is severely at-rophied. As a result, in addition to the vertical and transverse recession, the internal bone structure also alters. Late implants are usually smaller than the roots of the teeth being replaced. Temporary implants are designed for short-term use when immediate dentures need to be anchored or when orthodontic implants (ie, mini-implants or temporary anchorage devices) are being used to stabilize orthodontic appliances.Indications for ImplantsFixed implant-supported dentures have dem-onstrated long-term reliability equal to that of conventional xed prostheses. In the case of re-movable prosthodontics, implant-supported res-torations yield even better results than periodon-tally supported partial dentures. In any event, when treating edentulous arches, there is no al-ternative to anchorage with implants. The general indication for implant placement is when a remov-able denture cannot be integrated (eg, the patient has epilepsy) or when the patient has special oc-cupational requirements or specic pastimes (eg, musicians who play brass or wind instruments, actors, or politicians). Today implant-supported restorations are considered standard treatment because of their long-term functional reliability (Fig 9-4).Uncontrolled forces may be exerted because dentists do not perceive the intrinsic mobility of the implant or how osseointegration results in cushioning on loading and because periodontal receptors are absent. This must be offset by spe-cial shaping of the occlusal relationships.Single-tooth implants are indicated for closing a dental arch, for example after loss of a single tooth within an intact arch that is free of llings or caries. A single-tooth implant saves natural dental tissue, for example incisors that would otherwise have to be prepared as abutments. This key argu-ment in favor of implant placement is supported by the fact that a single-tooth implant usually has a better outcome than treatment with an anterior partial denture.Endosseous dental implants are indicated for small edentulous gaps, shortened dental arches, or reduced residual dentitions with large eden-tulous gaps and an unfavorable abutment ar-rangement; only implant support can guarantee the static relationships in these circumstances. Implants are especially indicated for edentulous arches that do not offer adequate retention for a complete denture because of advanced resorp-tive atrophy of the alveolar ridges or jaw defects.General contraindications include surgical risks, primarily in a wide variety of cardiovascular dis-eases and other organic conditions (eg, liver damage). Acute infections, leukemia, diabetes, and impaired immune resistance are also contraindi- 338Implant Terminologycations for implant placement. In addition, im-plant placement is ruled out in patients receiving drug treatment for rheumatic diseases, various skin and autoimmune diseases, AIDS, and other acute infectious diseases (especially in the oral cavity) as well as in patients with depression or women who are pregnant (Fig 9-5). If bone quality is reduced as a result of bone disease (eg, osteoporosis) or calcium excretion is increased in patients with renal insufciency, im-plant placement is equally questionable, just as it is in the case of patients who have severe physi-cal or mental disability or personality-altering psychopathies or who are poorly motivated and Fig 9-4 Implants that act as a tooth root replacement are suitable for universal use. If there are no specic contraindications, implants may be regarded as the standard treatment. This means it is possible to anchor a denture in the mouth without involving other teeth. Combined forms of anchorage are often used; that is, a removable partial denture may be anchored on implants and natural abutment teeth.Indications for dental implantsAnchoring abutments for partial dentures to bear prefabricated retentive elementsGap-supporting partial denture abutment in large edentulous gapsSingle-tooth implants for closing a dental archAnchoring abutments in edentulous arches for complete denturesContraindications to dental implantsGeneral contraindications in organic disease: Cardiovascular disease or liver diseaseAcute illnesses: Leukemia, diabetes, rheumatic diseases, or autoimmune diseasesLocal contraindications: Poor bone supply, occlusal anomaly, parafunction, or diseases of the oral cavityPersonal contraindications: Depression, psychopathies, mental disability, lethargy, or lack of motivationFig 9-5 Because implant placement requires considerable surgical and operational effort, a general contraindication exists if there are surgical risks that would also make other clinical procedures difcult; chronic or acute illnesses therefore rule out any implant placement. The patient’s personal disposition, such as poor motivation and psychopathies, may also prohibit dental implantation. 339Implantation Methodslethargic. A local contraindication exists if the bone supply is too small for an implant bed; if the vertical distances or alveolar ridges are too small or too large; or if there are anomalies of occlusal position, parafunctions, or a residual dentition re-quiring remedial work.Inammatory reactions at the marginal peri-odontium display patterns and features similar to inammation in the peri-implant tissue, which means there are no appreciable differences be-tween peri-implantitis and periodontitis despite the different biologic structures involved. Exces-sive stresses, which have only minimal inuence on periodontally damaged teeth, nevertheless have a much greater impact on peri-implant in-ammation.The part enclosed by tissue (ie, mucosa, bone) as far as the gingival collar is called the endo-structure and comprises the implant apex, im-plant body, and implant shoulder. This part has to divert the masticatory load into the bone. Com-pared with the functional root surface of natural teeth, endosseous implants have a smaller reten-tive surface in the bone. Therefore, endosseous implants are less able to absorb masticatory pres-sures than natural teeth.The exostructure is the part protruding out of the tegument into the oral cavity, which compris-es the neck of the implant and the abutment. This structure is the particular hallmark of an open implant, which pushes through the closed cover-ing of the body and can form an entry portal for pathogens. This structural feature is also a limit-ing factor in terms of indications.Implantation MethodsThe various methods of implantation are differen-tiated according to the localization of the dental implants.Transdental implants are sunk into the bone through the root canal of a tooth to lengthen the natural root (Fig 9-6). In an apically closed im-plantation, the transxation pin is moved into the periapical bone, whereas an apically open im-plantation is combined with an apicoectomy. This transdental xation system is a combination of conventional root pins and endosseous implants. The physiologic periodontium remains intact and a closed implant results.Transosseous implants are mandibular implants that run vertically through the entire mandibular body (Fig 9-7).Fig 9-6 A transdental (endodontic) im-plant is sunk into the bone through the root canal and lengthens the natural root. A distinction is made between apically closed implantation, in which the trans-xation pin is placed in the periapical bone, and apically open implantation, which is combined with an apicoectomy.Fig 9-7 A transosseous (trans mandibular) implant is placed caudally through the mandib ular body and extends into the tooth. 340Implant TerminologyIntramucosal implants are ball attachments that are sunk into the mucosa and xed basally to a re-movable denture (Fig 9-8). The intramucosal ball attachment is sunk into a cavity in the jaw mucosa that is lined with normal epithelium. The button-shaped retentive part sits rmly in the denture base and is removed from the implant bed when the denture is removed.Subperiosteal implants have a custom model-cast framework that is interposed between bone surface and periosteum (Fig 9-9). To do this, the bone surface is exposed and an impression is taken. The framework is accurately prepared by the model casting technique and placed onto the bone surface so that it can be subsequently re-covered with the periosteum and mucosa. The abutments puncture the mucosa at dened points.Endosseous-subperiosteal implants are sunk into the bone as well as interposed between the bone surface and the periosteum (Fig 9-10). The abutments break through the mucosa covering of the dental arch. These implants are produced us-ing the model casting method by preparing the implant bed into the bone and taking an impres-sion of the implant bed. Endosseous implants are root replacement parts that are sunk into the bone and puncture the mucosa of the dental arch (Fig 9-11). Endos-seous implants are placed into a form-tting cav-ity in the jawbone, which has been prepared with special instruments suited to the form of implant.Fig 9-8 An intramucosal implant is the ball attachment of a removable prosthesis that is sunk into the mucosa. The ball attachment is sunk into an articial cavity in the mucosa of the jaw, which is lined with normal epithelium.Fig 9-9 A subperiosteal implant is inter-posed as a metal framework between the bone surface and periosteum. After an impression of the bone surface has been taken, the accurately tting metal framework is prepared by the model casting technique and placed onto the bare bone surface.Fig 9-10 An endosseous-subperiosteal implant is sunk into the bone between the bone surface and periosteum; the abutment penetrates the mucosa of the dental arch. It is made by the model cast-ing method. The implant bed is prepared into the bone.Fig 9-11 An endosseous implant is sunk into the bone and punctures the mucosa of the dental arch. The part enclosed by tissue is the endostructure, and the part protruding into the oral cavity is the exo-structure; the mesostructure is the com-ponent that connects to the prosthetic replacement. 341Implant IntegrationImplant IntegrationBone displays various tissue reactions with re-spect to the implant material. The tissue reaction of the implant bed can be inuenced by micro-morphologic and macromorphologic improve-ments in retention of the implant body, for ex-ample special coating techniques, roughening, or screw threads.During implant healing, connective tissue en-capsulation of the implant (distance osteogen-esis) may occur, or a capillary gap may form between bone and implant (Fig 9-12). Collagen bers may also be deposited on the implant sur-face (contact osteogenesis) (Fig 9-13).Osseointegration is a direct structural bond with no separating layer of connective tissue between the bone tissue and the implant (Fig 9-14). This bond forms a rigid (ankylotic) connection in which periodontal bers are absent, and thus the im-plant has only minimal mobility. Mobility only oc-curs as a result of the elasticity of the surrounding bone. The bond between implant and bone must ensure the transfer of forces on loading of the im-plant.A biologic connection is created between epi-thelial cells of the mucosa and the implant neck: A junctional epithelium with basal lamina is formed out of glycoproteins (Fig 9-15). This tissue junc-tion has histologic and biochemical characteris-tics similar to those of the junctional epithelium in natural teeth and carries the epithelial mucosa up to the hard surfaces of the implant. This junction-al epithelium has a constant rate of renewal and thus prevents bacterial deposits on its surface. Similarly, neutrophilic granulocytes accumulate in this area, and these are able to resist periodon-tal or peri-implant infections. In addition, in the tissue area—similar to the situation with natural teeth—a system of circular connective tissue -bers running perpendicular to the implant surface is formed that xes the mucosa to the implant. It has not yet been proved whether these bers are anchored rmly to the implant surface.Fig 9-12 (top) When connective tissue encapsu-lation occurs or a capillary gap forms between the bone and the implant during the course of implant healing, this is known as distance osteogenesis.Fig 9-13 (center) Contact osteogenesis is complete bony (osseous) containment of an implant without any separating layer of connective tissue.Fig 9-14 (bottom) Ion exchange can occur if there is close chemical ongrowth of bone onto the implant (exchange osteogenesis). During healing, the implant is incorporated into the physiologic metabolism of the growing bone. This functional ankylosis is known as osseointegration. 342Implant TerminologyAfter implant healing is completed, the implant has to be subjected to normal loading to ensure physiologic bone maintenance because only load-ed bone will stabilize and be stimulated to form new tissue.Quality of Implant MaterialsImplant materials are classied into four groups:• Autogenous materials (from the same body)• Homologous materials (from the same species)• Heterologous materials (from a different spe-cies)• Alloplastic (nonbiologic) materialsAutogenous implants are derived from the same organism, for example extracted teeth or endogenous bone grafts. Homologous implants are tissue parts transferred from other people. Heterologous implants are tissue parts trans-ferred from a different species. Alloplastic materi-als are metals and their alloys, ceramics, or plas-tics. The requirements for implant materials are mechanical stability and biocompatibility.The mechanical properties of implant materials and bone must be approximated to each other so that masticatory forces do not give rise to shear-ing stresses between bone and implant bond. The aim is to nd a material with sufcient strength and a modulus of elasticity matched to that of bone. Metals have sufcient strength, elongation at fracture, and variable elasticity, while ceramic has high fracture toughness.Implant material is biocompatible if the cells in contact with the implant can participate un-impeded in the natural process of metabolism. Tissue that is in contact with nonbiocompatible materials may display antibody reactions, aller-gies, encapsulation, and toxic and inammatory reactions and ultimately die. On the other hand, the implant material may corrode in the body, or it may be leached out, abraded, or resorbed.In dental implantology, alloplastic materials are used almost exclusively because their availability is virtually unlimited, they are easy to store, and they can be produced to a dened and controlla-ble quality level. However, foreign-body reactions to alloplastic materials may occur. In particular, metallic implants may have complex interactions with the implant bed tissue, resulting in corrosion and development of metallosis in the implant bed tissue. Metallosis can lead to a connective tissue separating layer between bone tissue and metal implant.Corrosion is damage to metals or alloys caused by chemical or electrochemical reactions. Tissue uids and saliva, in which ions and salts are dis-solved, act as electrolyte solutions in the body that attack the metal. Galvanic processes between the metallic materials of the implant and super-structure, contact and friction corrosion, as well as local elements may give rise to other damage to the implant and the tissue of the implant bed.The movements of ions in tissue disrupt the natural physiologic processes, can disturb the biologic equilibrium in cell growth, or can trig-ger allergies. Metal ions also get into the diges-tive tract via saliva and reach organs of the body where they accumulate beyond the physiological-Fig 9-15 An epithelial join between the mucosa and the im-plant surface is formed on the smooth or polished neck of the implant. Junctional epithelium is formed with a basement membrane that displays similar characteristics to marginal peri-odontium. A buildup of leukocytes may also be noted in this tissue area. At the crestal transition (passage through the al-veolar bone), modern implants have special surface structures that can improve attachment in the hard cortical layer. 343Implant Material and Tissue Reactionly tolerated limit. The transport of ions can dam-age remote organs.Metals can protect themselves against various forms of corrosion by means of a passivating surface layer. Many metals spontaneously form a passivating protective layer by oxidation; these metals are passivatable. An oxide lm is formed over the entire metal surface, which prevents the exchange of charge carriers with other media and protects the metal against further corrosion. This passivation layer can be mechanically damaged but regenerates quickly by renewed passivation.Some base metals form stable, highly noble surface oxides as a passivation layer even when the oxygen supply is minimal. Titanium and its alloys display particularly rapid growth of a pas-sivation layer; other implant alloys contain pas-sivating additives. Gold and platinum alloys, as precious metals, are corrosion resistant even without a passivating protective layer.Saliva forms a closed electrical circuit between jawbone and implant, where local galvanic cur-rents transport the corrosion products. The depo-sition of corrosion products rst causes dark dis-coloration in the implant bed tissue; cell activity is impeded, and aseptic necrosis may ensue. These reactions do not occur with titanium. Ceramics and plastics are corrosion resistant but can be re-sorbed by bodily uids.Implant Material and Tissue ReactionDental implants have to fulll extremely varied requirements because they protrude into the oral cavity and are in contact with various types of tis-sue, such as jawbone, periodontium, and gingiva. They are made almost exclusively of alloplastic material, such as metals, ceramics, and compos-ites (Fig 9-16). The mechanically stable metallic materials include titanium and titanium alloys. In terms of nonmetallic implant materials, acryl-ics, aluminum oxide ceramics, biolite carbon, glass-ceramics, calcium phosphate ceramics, and hydroxyapatite ceramics have been tried and, in most cases, rejected.Composite materials are the coatings applied to implant surfaces, for example titanium plasma, hydroxyapatite, or biolite carbons, to achieve di-rect ongrowth of bone onto the implant.Alloplastic implant materials can be classied as biotolerated, bioinert, or bioreactive, depend-ing on their suitability for achieving intensive osseointegration and thus according to their de-gree of biocompatibility. Biotolerated materials (mostly metals) form a separating layer of con-nective tissue between the implant and its bony Biotolerated for distance osteogenesis: Nonprecious alloys (gold titanium)Bioinert for contact osteogenesis: Aluminum and zirconia-ceramicBioreactive for ongrowth of bone: Hydroxyapatites and calcium phosphate bioglassesComposite materialsFig 9-16 Dental implants are almost exclusively made from alloplastic (nonbiologic) materials. Metals have the most favorable physical properties, such as hardness, tough-ness, fracture strength, and elasticity; among metals, only pure titanium is sufciently biocompatible. Materials are classied as biotolerated, bioinert, or bioactive, depend-ing on their degree of biocompatibility. 344Implant Terminologybed, a process known as distance osteogenesis. The interlayer of connective tissue weakens the retention of the implant and may arise because of the interaction of bone with toxic metal ions or when the implant is loaded during the healing phase. Bioinert materials (mostly oxide ceramics) hardly release any ions and do not react with the tissue of the implant bed. The bone attaches di-rectly to the implant material, which is known as contact osteogenesis. Bone regeneration extends right up to the implant surface. Bioreactive ma-terials (mostly hydroxyapatites, tricalcium phos-phate) actively create close chemical ongrowth of bone. Calcium phosphate ions are released from the apatite portion of these materials, and these ions become involved in the physiologic metabo-lism of the growing bone during healing of the implant. Bone is deposited in the surface pores of the implant without an interlayer of connective tissue. Faster osseointegration may ensue.Osseointegration refers to the rigid (ankylotic) join between implant and bone, which is evident as a direct transition from bone to implant with-out an intermediate layer of connective tissue. Ion exchange between implant and bone (exchange osteogenesis) occurs in this functional join; the implant appears to be incorporated into the phys-iologic metabolism of the growing bone.The mechanical roughness of the implant sur-face in its micromorphology is vitally important. This is because the macroscopic mechanical re-tentions of the bone-to-implant contact ensure primary stability during the healing phase. The biologic reaction of active bone growth results in mechanical xation in microscopically small un-dercuts when the bone grows into surface pores.Surface roughness with a depth of 1.4 µm cre-ates stable bioadhesion of the implant in the im-plant bed. It is impossible to ascertain exactly what inuence the chemical composition of the implant coating has on the stability of the bone-to-implant connection. However, the proven suc-cess rate of over 95% of implants without articial overlying mineral or protein seems to indicate the functionality of a roughened surface without a coating. To achieve this, healing must take place in an absolutely immobile state because this is the only way bone can grow onto the implant surface. If there is any mechanical loading, bone contact is lost and separating layers of connec-tive tissue will form.As a result of this roughness, the surface is more wettable, and bone contact is markedly im-proved. The rough surface also prevents the for-mation of intermediate layers of connective tis-sue, increases the formation of new bone, and enhances the bioadhesion of the bond between implant and bone.The elastic behavior of implant and bone de-termines the functional integration of the implant into its bony surroundings. The greater the con-gruence of the elasticity moduli, the better the in-growth of the implant, and the formation of new bone will also be stimulated. The elasticity of tita-nium can be perfectly adapted to the bony bed.Titanium as an Implant MaterialTitanium is currently the most widely used im-plant material because of its mechanical and bio-compatible properties. The mechanical character-istics of pure titanium, expressed in a 0.2% yield strength and modulus of elasticity, vary widely depending on the admixture of iron and oxy-gen. Titanium surfaces bind oxygen within frac-tions of a second and release iron equally well; different strength values arise, depending on the amount of the admixtures. The yield strength and modulus of elasticity also increase as a result of the strain hardening after cold deformation. This effect is given as a grade, whereby the greatest hardening of pure titanium reached upon cold de-formation is grade 4.An increase in the mechanical values is achieved by forming alloys with aluminum and niobium (or vanadium). Both additives partly prevent the trans-formation from the body-centered high-temperature phase to the hexagonal low-temperature lattice, so that a crystal mixture from both phases exists. This two-phase crystal mixture is known as (α−β)-titanium and displays lattice stresses that are reected in a marked increase in these values. However, biocompatibility seems to suffer in the process.The excellent biocompatibility of pure titanium is due to its passivatable surface. Pure titanium is an extremely ignoble metal in the electrochemical series and spontaneously forms a passivating ox- 345Titanium as an Implant Materialide on the surface, which displays bioinert behav-ior in tissue. The passivated titanium surface does not corrode, and only a few titanium ions get into the surrounding bone. Titanium ions do not ap-pear to prevent bone apposition. Titanium with its various compounds is in any case a natural con-stituent of the body, and as yet reports of allergic reactions to titanium have been extremely rare, with an estimated prevalence of 0.6%. Therefore, titanium should preferably be used non-alloyed because alloy constituents may release ions due to corrosion.Pure titanium has become almost fully estab-lished as an implant material, its excellent bio-compatibility and the roughening of the surface being crucial prerequisites to osseointegration. Pure titanium can be planed to a very smooth n-ish by machining of the surface, leading to good epithelial attachment in the emergence area and facilitating excellent cleaning. However, distance osteogenesis with poor quality of anchorage aris-es in the implant bed.Various methods are used to roughen the implant surfaces, such as acid etching, airborne-particle abrasion, anodic oxidation, and application of coatings. In the acid-etch technique, the surface processing is done with various combined acids that roughen the titanium surface in the microm-eter range (approximately 1 µm). The osteoblasts are able to embed in this rough surface, resulting in improved bone apposition. Surface machining by airborne-particle abrasion with abrasives, such as aluminum grit size 1.2 to 2.2 µm, produces medium roughness of 1.4-µm depth, which is the most advantageous roughness for contact osteogenesis. As blast particles may remain in the surface depending on the blasting medium, the abraded surfaces are then acid etched to pro-duce an even ner surface relief. A further etching process with isotonic sodium chloride solution alters the wettability so that bone apposition is accelerated (Fig 9-17). If the implant is also treat-ed with ultraviolet C radiation after the combined etching processes, the surface tension is switched Fig 9-17 Smooth titanium surfaces are hydrophobic (ie, they repel water). Faster osseointegration can be achieved by hydrophilic, osteoinductive properties, as in the case of the SLActive implant surface from Straumann. The surfaces interact with the tissue and accelerate cell activity so that growth-promoting cytokines (bone morphogenetic proteins) are released. In the SLA production process, the implant surfaces are airborne-particle abraded with large-grit particles followed by acid etching with heated hydrochlo-ric and sulfuric acid. The acid etching produces a microroughness of 2 to 4 µm. The surface is subsequently conditioned in nitrogen and stored in an isotonic salt solution. Bone contact with the conditioned implant surface is considerably improved, which shortens the healing process to about 3 to 4 weeks and speeds up osseointegration. Immediately after implant insertion, substantially more bone is formed on the enlarged SLActive surface; in special cases, there is an increase in bony tissue. (Illustration courtesy of Straumann.) 346Implant Terminologyfrom negative to positive, the osteoblast reaction increases, and more intensive bone-to-implant contact results.Surface coating by anodic oxidation (anodizing) is performed by means of spark discharge in an aqueous electrolyte where calcium phosphates are amorphously integrated (Fig 9-18). Accelerat-ed bone regeneration and more intensive osseo-integration occur at the porous implant surface. Surface coating with hydroxyapatites is done by sintering in an immersion bath. The chemical de-position of nanoparticles is intended to produce fast osseointegration with high bone-to-implant contact.The implant surface can be conditioned and enlarged sixfold by coating with titanium plasma (Fig 9-19). This method involves welding particles of titanium powder onto the titanium in a layer 30 to 40 µm thick at high temperature; this produces a dened roughness of 1.5 µm.Zirconia ceramic is a polycrystalline material that exists in three chemical phases with different prop-erties: monoclinic, tetragonal, and cubic. The tetra-gonal phase, which is suitable as an implant ma-terial, is metastable at room temperature and can be destroyed by thermal stress (friction heat dur-ing grinding). Zirconia is biocompatible and can be radiographically depicted like metal. It has Calcium phosphate layerProtein structuresBone substanceTitaniumTitanium oxideFig 9-18 (top) Surface conditioning of titanium implants by electrochemi-cal anodizing produces an oxide layer of 15 to 20 µm into which 40% calcium phosphates are amorphously integrat-ed under spark discharge. (Illustration courtesy of ZL Microdent.)Fig 9-19 (bottom) The physically measurable surface can be enlarged sixfold by means of plasma coating. The resulting roughness of 1.4-µm depth improves osseointegration of the implant. Given the concentration of calcium phosphates in the implant surface, proteins should be better absorbed and healing of the bone wound promoted. Faster healing of the implant has not been observed with coated implants. 347Forms of Endosseous Implantshigh strength, is extremely break resistant, can be stained to natural tooth color, and is superior to titanium in terms of esthetics and plaque resistance.Aluminum oxide ceramics are chemically, ther-mally, and mechanically highly resistant and dif-fer considerably from bone in terms of elasticity, so shearing forces arise in the bone-to-implant bond during loading. The aluminum oxide sur-face behaves in a bioinert fashion, which means the bone structure is densely deposited.Calcium phosphate ceramics are bioactive ma-terials comprising calcium oxide and diphospho-rus pentoxide; they are similar to mineral bone. Hydroxyapatite ceramic and tricalcium phosphate ceramic are of clinical relevance.Forms of Endosseous ImplantsEndosseous implants are open implants that pro-trude out of the body’s surface. They are dictated by the anatomical conditions, such as shape and position of the maxillary sinus and the mandibular canal. Following are different types of implants:• Cylinder implants• Hollow-cylinder implants• Screw implants• Blade implants• Abutment-and-pin implants• Needle implantsCylinder implants (or cylindric implants) are full-body implants whose surfaces are rough-ened by chemical or mechanical processing or by a plasma coating (Fig 9-20). As a result, the sur-face is enlarged and bond stability is increased. Some cylinder implants have apical perforations, which ll with bone during the loading-free heal-ing phase to achieve additional stabilization. For cylinder implants, system-specic bone cutters must be used to prepare a form-t implant bed. The implant can be tapped into the cavity with a seating instrument until it wedges in the can-cellous bone in a press t. Intramobile cylinder implants (eg, IMZ implant system) comprise the implant body and a cushioning component, the intramobile connector.A hollow-cylinder implant comprises a rotation-ally symmetric, perforated implant body that has a large implant anchorage area and, because of its small implant volume, requires only minimal loss of bone substance when preparing the im-plant bed (Fig 9-21). The implant bed is cut with a hollow cutter at low speed, which is intended to produce a form-t implant bed with uniform pres-sure distribution to the bony tissue. Various types of hollow-cylinder implants are available (eg, ITI hollow-cylinder implants, Straumann) as single cylinders and double cylinders, which support the abutment on a connecting bar. Hollow cylinders have an implant stiffness that is similar to bone, which reduces the stresses between bone and im-plant when the bone grows into the perforations.Screw-type implants have a cylindric or tapered implant body with screw threads (Fig 9-22). The surface of metallic screw implants (mostly titani-um) can be coated. Self-tapping threads are distin-guished from those that are screwed into precut cavities. The thread anks are intended to guaran-tee uniform transfer of force into the bone with-out stress peaks. Self-tapping threads sit rmly in the loose cancellous bone and are immediately loaded. On precutting of threads, contact surfaces for the implant may break off, but the bone chips are ushed out before the implant is screwed in place, thus guaranteeing better healing. Tapered screw implants have an approximate root shape so that little bone tissue has to be sacriced for immediate implant placement.Blade implants are extension implants with greatly expanded, at, disk-shaped, or even double-blade–shaped implant bodies (Fig 9-23). Extension implants offer large, functionally ef-fective surfaces for bone apposition. The forms of implant commonly used today emerged from extension implants. Blade implants may be indi-cated where there is an extreme horizontal lack of bone and when a rotationally symmetric im-plant cannot be inserted. The drawback to blade implants lies in the high bone loss if explantation is required. This is because the implant needs to be widely exposed if it has to be removed.Abutment-pin implants are endosseous implants that have a pinlike implant shaft and abutment-like wing extensions for antirotation protection (Fig 9-24). The slender aluminum oxide ceramic pins were once used as a late implant for single-tooth restoration in the maxillary and mandibular 348Implant Terminologyanterior region. These delicate tooth root replace-ments are no longer used because of the risk of fracture.Needle implants are long, needle-shaped metal pins made of tantalum (Fig 9-25). The surface-ground pointed needles were either self-drilling and driven into the bone with hammer blows or self-tapping and inserted with a contra-angle. Several needles were always inserted, for exam-ple three crossing needles or seven to ten needles as a needle path. Needle-shaped implants are no longer used because of the high failure rates.Fig 9-20 Surfaces of whole-cylinder implants may be roughened by chemical or mechanical processing or by plasma coating, which displays bond stability. Some cylinder implants have apical per-forations.Fig 9-21 Hollow-cylinder implants are perforated tubes with a double bonding surface. Only a little bone tissue is milled out to prepare the implant bed.Fig 9-22 Screw-type implants with a cylindric or tapered implant body are cre-ated with threads that evenly transfer force via the thread anks. The surfaces can be coated. Screw implants may have self-tapping threads.Fig 9-23 Blade implants are extension implants with a double-blade shape and a at body that provide functionally effec-tive surfaces for bone apposition. They are only indicated where there is an ex-treme horizontal lack of bone.Fig 9-24 Abutment-pin implants, which are no longer used today, were pin-type endosseous implants with abutment-type wing extensions for antirotation pro-tection. They were made from aluminum oxide ceramic and were not very fracture resistant.Fig 9-25 Needle implants, which are no longer used today, were made from tantalum with surface-ground points that were driven into the bone with hammer blows. Several needles were always in-serted. 349Design of Endosseous (Permucosal) ImplantsDesign of Endosseous (Permucosal) ImplantsThe parts of an implant are individually function-ing or morphologically distinct sections, such as the implant apex, implant body, implant shoul-der, implant neck, and abutment (Figs 9-26 and 9-27). The implant body is the part of a root re-placement sunk into the bone (endosseous), in which the implant shoulder and implant apex can be differentiated. The two types are hollow-body and full-body implants. Hollow-body implants are perforated, hollow cylinders (ITI hollow-cylinder implants) with an internal and external implant anchoring surface, a smaller implant volume, and a deformation behavior similar to that of bone. Full-body implants are cylindric or tapered and enable osseointegration at the external surface as bone is able to grow into a basal perforation in the implant and stabilizes the implant against torsion.Implant bodyImplant neckImplant shoulderImplant apexImplant abutmentSuperstructure/tertiary componentExostructure/ secondary componentConnecting screw/ mesostructureEndostructure/ primary componentFig 9-26 Structural components of an implant.Fig 9-27 The implant bed is the bone cavity for the implant body; it must be rigorously prepared and must not harm inter-nal bone structures, such as the mandibular canal in the man-dibular body, as shown here. 350Implant TerminologyThe implant apex is the lower (apical) portion of the implant body, by means of which the force directed vertically onto the implant is transferred to the bone. In screw implants, part of the verti-cal force is directed into the bone via the screw threads.The implant shoulder forms the transition from implant body to implant neck or to the abut-ment elements. This protruding initial part of the implant body is sunk in the bone and lies in the area where the compact bone is penetrated. The implant shoulder is narrow, high-gloss polished, and beveled buccally to allow esthetically advan-tageous shaping of the replacement tooth.The implant neck lies in the area where the mu-cosa is penetrated, between the implant body inserted in the jawbone and the abutment. The coronal part of the implant body is sometimes known as the implant head. The implant neck is particularly pronounced in one-piece implants and lies slightly supragingivally so that the implant shoulder lies markedly above the alveolar ridge. The implant neck is an inverted cone or is slightly collar-like to protect the peri-implant transition against vertically directed stresses. It is polished to a high gloss to prevent plaque from being de-posited. The mucosal collar should attach without irritation to a smooth, rounded implant neck.A junctional epithelium, an epithelial adhesion, and a brous system for attachment of the mu-cosal collar may be formed. To adapt the height of the implant neck to the mucosal thickness, ex-changeable spacer sleeves can be tted. These spacer sleeves can be replaced by new, high-gloss polished components if they become badly contaminated or damaged.The implant post, also known as the abutment, is the buildup protruding into the oral cavity; it sits on the implant neck and directly receives the superstructure or a special mesostructure. In one-piece implants, the abutment is rmly joined to the implant body, whereas in two-piece implants, the implant body and the abutment are separated and joined together by a separate screw connec-tion (Fig 9-28). The implant body is generally re-ferred to as the implant for short.The connection between implant neck and abut-ment must ensure anti-rotation protection, free-dom from gaps, and adequate mechanical stabil-ity (Fig 9-29). Abutments can be cemented into, screwed into or onto, or force tted onto the im-plant body, and they are then rigidly joined to-gether.An intramobile element made of plastic can also be inserted between implant and super-structure (Fig 9-30). This intramobile element is Fig 9-28 A distinction is made between one-piece and two-piece implants. One-piece titanium implants with a very small diameter are usually intended for tem-porary use as provisional implants. Two-piece implants consist of the implant body and the abutment.Fig 9-29 The quality of the connection between implant body and abutment affects the security of the abutment against tilting and rotation. A distinction is made between internal and external connections. 351Implant-Abutment Connectionexible and is intended to imitate the resilience of the periodontium when a denture with mixed support (seated on implants and natural teeth) is being fabricated.The superstructure is the prosthetic replace-ment, which can be cemented onto the abutment in a removable or xed fashion, bonded, or screwed in a partly removable way. A ready-made cylinder can be inserted between superstructure and abutment; it can take the form of a prefabricated bondable or screwable titanium or gold cylinder, ceramic coping, or burnout plastic cylinder.The implant disk in two-piece implants is an abutment in the form of a circular ledge on the implant body that ends with the superstructure and ensures an optimal marginal t.Implant-Abutment ConnectionIn two-piece implants, the form and stability of the connection between implant and abutment needs to be examined in more detail. For pros-thodontic use, it is essential to clarify what antiro-tation protection exists, whether the connection is tapered or parallel, and whether an external or internal connection exists.Antirotation or anti-tilting protection refers to the connection being secured against torque in the vertical connection axis, which is especially important in single-tooth restorations. Several implants that are rigidly connected (splinted) by a partial denture or denture framework are not sub-ject to rotation. In these circumstances, non-axial forces can tilt the implant-abutment connection, which can lead to loosening of the implant screw. Antirotation protection must exist with internal and external connections and can be created by a suitably angled connection prole (eg, internal or external hex) (Fig 9-31).Tapered or parallel contact surfaces in the implant-abutment connection affect the reliabil-ity of the connection. The inclination of the con-tact surfaces varies from parallel-walled to conic-ity and from 1.5 to 11 degrees. Very steep-walled conical connections develop very high surface pressure in the contact area so that permanent conical connections can arise as a result of cold welding.External and internal implant-abutment connec-tions can loosen or break due to minimal loading movements. Comparatively speaking, internal con-nections prove more stable than external connec-tions, but a long internal connection will weaken the implant body so that a fracture could occur there. If several implants are inserted to support a long-span partial denture, an external connection Fig 9-30 Structural components of an implant with an intramobile cushioning component.SuperstructureIntramobile cushioning componentTertiary screwTitanium insert (carries the cushioning component) Implant body (coated, perforated cylinder implant) 352Implant Terminologyin the case of divergent implant axes offers the advantage that the partial denture can be screwed directly in place. With internal connections to nonparallel implant axes, the abutments have to be parallelized for a common path of insertion.External connections can be shaped in the form of an external hex (Fig 9-32). The implant as a full screw bears a low, parallel-walled external hex ring above the implant shoulder, through which the retention screw is guided. The connection is rotationally stable but might tilt as a result of non-axial forces, which may loosen the screw mecha-nism and lead to fracture of the connection (eg, Brånemark implant, ZL Microdent implant).Implant systems with internal anchorage have one path of insertion, which results from the im-plant axis. Where there are several implants, the variations in the path of insertion must be bal-anced by the abutments in order to receive splint-ed structures. The abutments can either be par-allelized or angled toward the implant axis (Fig 9-33).Internal connections with a parallel-walled tube-in-tube connection are rotationally stable if they have several internal grooves for a form-t con-nection (eg, Camlog implant). Internal connections, in which the tapered area is octagonally or hex-agonally shaped, are just as rotationally secure as tapered internal connections with an additional hex (eg, Straumann implant). Internal tapered connections without additional antirotation pro-tection allow for 360-degree universal positioning of the abutment. Rotational stability is achieved with a steep tapered connection (1.5-degree ta-per). This type of connection is suitable for par-ticularly short implant bodies at least 5 mm long (Figs 9-34 and 9-35).One-piece implants are predominantly zirconia ceramic implants and implants with very small diameters or temporary titanium implants. The implant body and the abutment form a unit and are therefore not submerged during healing. One-piece implants with a very small diameter (1.8 mm) have a spherical abutment for anchoring overdentures. They can be inserted by minimally invasive surgical techniques and can be immedi-ately loaded.Fig 9-31 The abutment is placed into or onto the connection prole and xed with a screw. The stability of this connec-tion depends on screw diameter and the anti-tilting protection.Fig 9-32 An external connection be-tween the implant parts can be rendered rotationally secure by an angled connec-tion prole, for example a hexagonal pro-le. 353Implant-Superstructure ConnectionTemporary implants have a diameter around 2 mm and are used during postextraction healing or after placement of nal implants; osseointe-gration is not the goal.Zirconia ceramic implants come in a variety of forms and can be individualized by preparation. The impression is taken in the same way as for a normal tooth preparation.Implant-Superstructure ConnectionSuperstructures can be screwed onto an abut-ment or a bar or, like conventional restorations, can be cemented onto individual cementation abutments of the implants that have been insert-ed (Fig 9-36). Single-tooth restorations can also be placed onto ceramic abutments by the acid-etch technique with composites.Screw ttings can be guided occlusally and transversally and are used for partly removable superstructures. Ease of removability makes re-pairs and hygiene measures easier and is essen-tial for long-span partly removable partial den-tures. Screws are used for xing onto individual abutments and onto bars. The occlusal or trans-verse screw xation of implant-borne super-structures is being used less and less frequently because minor inaccuracies in fabrication cannot be tolerated—especially on long-span partial dentures—and it might not be possible to use a partial denture that ts onto the model (Fig 9-37).Occlusal screw connections must be covered after insertion and exposed again before undoing the screw connection. They have poor esthetics and in some circumstances may impair mastica-tory function.Fig 9-33 An internal connection can be shaped to have parallel walls or to be tapered and rendered rotationally secure by means of various internal grooves. In addition to an internal hex, three to eight grooves can be created. The more grooves, the more ways the abutment can be positioned. Universal positioning options offer a rotation-ally symmetric connection without additional antirotation protection.Fig 9-34 In extremely short im-plants, the internal connection takes up the entire 5-mm-long implant body, while rotational stability arises from a steep-walled (approximately 1.5-degree) tapered connection in which the sides of the cone can fuse.Fig 9-35 The connection pro-le of an internal cone offers no primary antirotation protection. The two parts of the implant are created by an additional screw connection. 354Implant TerminologyTransverse screw connections are not as prob-lematic esthetically and functionally; the tension-free seating is easier to produce, but they do result in large gaps that cause taste and odor problems. They are difcult to handle and require a voluminous, orally prominent construction with an unsightly screw hole.Cementation is being used more and more of-ten because it can compensate for all the draw-backs of screw connections (Fig 9-38). Cementa-tion has the following advantages:• Cemented superstructures do not have the same esthetic and functional limitations as oc-clusal screw connections, and occlusal surfaces do not have to be perforated for a screw.• A superstructure can be removed again if tem-porary cements are used.• The cement layer compensates for inaccuracies of t caused by fabrication and ensures tension-free seating of a partial denture structure.• Different implant axes can be better compen-sated for.• Cemented, implant-supported single crowns do not differ from natural teeth in terms of wearing comfort, cleanability, and amount of aftercare.• Use of customized abutments is possible so that the path of insertion, gingival contour, and position of the crown margin can be perfectly shaped.Fig 9-37 Screw connections guided occlusally are functionally critical and will not tolerate t errors; even minor fabrication errors might make it impossible to insert the screw tting. The screw hole must be covered occlusally, which may be an es-thetic drawback.Fig 9-36 Superstructures can be screwed onto the abutment. The screw connection can be attached occlusally or transver-sally. Transverse screw connections are guided from the me-siolingual direction for esthetic reasons; they allow tension-free seating but are difcult to handle and create gaps that can cause odor problems.Fig 9-38 Transverse or occlusal screw connections of super-structures are only rarely used because of the described de-ciencies (minimal fabrication tolerance, esthetic shortcomings, and difculty in handling). Cementing the superstructure onto the abutment can compensate for all the disadvantages: Both t errors and gaps are offset by the cement layer. 355Special Forms of ImplantsThe disadvantage of denitive cementation is that the superstructure cannot be removed with-out being destroyed; that is, if the screw connec-tion between implant and abutment breaks, the superstructure has to be replaced. Therefore, a rotationally stable, reliable, and loadable implant-abutment connection is essential.When prosthetically restoring alveolar ridge defects that cannot be remedied surgically by bone augmentation, a removable construction must be used for optimum oral hygiene. Double crowns or a bar construction can be cemented permanently onto the abutments, while the re-placement covering the mucosa and designed as a partly removable restoration can be screwed onto the substructure. A partial denture structure with alveolar ridge replacement made of ceram-ic can also be permanently cemented in place if cleanability is guaranteed.Implants can be joined together rigidly by the superstructure or splinted. The implant-borne restoration then distributes all stresses to the splinted implants and reduces the loading. As in conventional prostheses, a distinction is made between primary splinting by xed structures and secondary splinting by removable structures. The more implants are included in the splinting and the larger the supporting polygon, the smaller the loading on the individual implant.Concepts of occlusion for implant-supported restorations do not differ from the concepts of conventional prosthetics. Canine guidance or tooth-group guidance can take place as much as with periodontally supported dentures. Unilateral or bilateral balanced occlusion can be construct-ed in quasi-complete dentures that are anchored with implants, depending on the quality of the denture-bearing mucosa.Special Forms of ImplantsImmediate implants are conical tooth replace-ment parts that are inserted immediately after extraction of a tooth to shorten the edentulous period. Immediate implant placement takes place right away or a few days after a dental extraction when no bone loss has yet taken place. An ap-proximate form t between implant and socket can be achieved by root-analog, tapered screw implants. Implant screws with a large-volume screw core can lie fully up against the alveolar bone for an optimal implant-bone connection. Immediate implant placement can only be per-formed if the socket or extraction wound is not infected and there are no apical defects. Imme-diate implant placement is usually necessary if traumatic tooth loss occurs because of an acci-dent or if the tooth can no longer be preserved after a tooth fracture (Figs 9-39 to 9-44).Delayed implant placement refers to implant insertion that takes place after epithelial wound healing is completed, about 6 to 8 weeks after extraction of the tooth. At that stage the socket is grown through with connective tissue without fully developed new bone.Interim implants are implants with an ultrasmall diameter (2 mm) with which immediate partial dentures are anchored during the healing phase of the denitive abutments. Complete or partial dentures can be supported on such temporary implants to accomplish the following:• Protect denitive implants against unwanted stresses during the healing period• Facilitate guided bone regeneration in preim-plant augmentation or sinus elevation proce-dures• Allow a temporary immediate restoration be-fore delayed implant placement• Fix orthodontic appliances (mini-implants)• Fix the drill template for denitive implant place-mentFor transitional implants, a pilot hole is placed in the bone with a spiral drill, and the interim implant is screwed in place. These implants are loaded immediately after placement and removed again after the interim denture–wearing period.Mini-implantsSpecial endosseous palatal implants or mini bone screws are known as mini-implants; they provide positionally stable xation and can be used for stationary anchorage of orthodontic appliances (Fig 9-45). Orthodontic stresses on anchoring teeth to which the appliances would otherwise be xed can thereby be avoided. Other anchoring methods, such as headgear or maxillomandibu-lar elastics, are not necessary, which reduces the 356Implant TerminologyFig 9-39 After traumatic tooth loss, a replacement tooth root can be inserted into the extraction wound, provided that the socket is preserved and not infected.Fig 9-40 The socket is cleaned and deepened to the implant length in the apical area. The pilot hole acts as a guide for the implant cutter.Fig 9-41 The implant bed is prepared with cutters of increasing diameter with-out damaging the lingual and vestibular walls of the socket.Fig 9-42 The largest implant cutter ex-cavates the implant bed to the diameter of the eventual implant. Cutting is always done under cooling with physiologic sa-line.Fig 9-43 The nished implant bed for the root replacement roughly follows the conical shape of the socket or the ana-tomical shape of the tooth root.Fig 9-44 The stepped immediate im-plant has no thread but is tapped into place. Two-piece components may be used where submerged healing of the implant body takes place.Fig 9-46 Endosseous mini–bone screws with 1.8- to 2.0-mm thread diameter and a 6- to 8-mm thread length can be used for orthodontic anchorage.Fig 9-45 Mini-implants create absolute anchorage by which orthodontic tooth move-ment can be performed in all three spatial dimensions. These are very short palatal implants that have to be removed after the orthodontic measures. 357Augmentation Methods in Implantologymechanical complexity of orthodontic appliances. The force exerted is direct; for example, when in-clined teeth are to be uprighted or intruded, teeth need to be lifted out.Anchorage with mini-implants is indicated if there is no possibility of periodontal anchorage, if there are too few teeth, or if extraoral anchorage is rejected in adulthood. The use of mini-implants also makes orthodontic treatment possible in periodontally damaged dentitions. Mini-implants are used in pre-prosthetic measures when abut-ment teeth need to be parallelized for the planned restorative work. In this situation, the implants can be tted into the dental arch and later used for prosthodontic purposes.Special mini-implants are placed outside the dental arch. They are moved palatally as palatal implants because endosseous implants cannot be inserted in the alveolar process or the dental arch before skeletal growth is completed. Healing time is 10 to 12 weeks, before orthodontic forces can be applied. The implants have to be surgically removed after use, which reduces patient acceptance.Endosseous mini-implants are therefore being used increasingly. With a thread length of 6 to 8 mm, thread diameters of 1.8 to 2.0 mm, and spe-cially prepared screw heads, they are intended for orthodontic anchorage (Fig 9-46). These mini-screws can be inserted and removed in a mini-mally invasive procedure. They largely protect the anatomical structures (tooth roots, nerve struc-tures) inside and outside the alveolar part of the jawbone and create favorable lever conditions when they can be inserted in the dental arch.Augmentation Methods in ImplantologyIf implants of adequate length and diameter can-not be placed in an atrophied jaw, the bony bed can be optimized by extended surgical interven-tions, creating enough space for implant insertion (Fig 9-47). Various augmentation methods are used for this purpose, such as alveolar ridge aug-mentation by means of bone grafts, alveolar bone splitting and split osteotomy, elevation of the si-nus oor or sinus elevation with bone condensa-tion, and alveolar ridge distraction. As the can-cellous bone (spongy-type bone) is permeated by numerous cavities containing bone marrow, there is less apposition contact with the implant; this can be remedied by condensing the bone.Alveolar ridge augmentation by means of bone grafts or onlay grafts refers to augmentation of the implantation area with bone grafts that are primarily harvested from the retromolar region, the chin area, or the iliac crest (Fig 9-48). The grafts can be xed onto the atrophied alveolar ridge with screws or plates or with the implant itself (Fig 9-49). For this purpose, an implant cav-ity can be drilled before the graft is harvested. The Fig 9-47 Severely atrophied ridge re-gions are only suitable for implant place-ment if an adequate bony bed is created by surgical measures.Fig 9-48 Alveolar ridge augmentation refers to an augmentation method in which a piece of autogenous bone (from the patient’s own body) is tted onto the ridge. Grafts harvested from jawbone are the most suitable.Fig 9-49 The graft can be xed to the augmentation area with screws. If an im-plant cavity is created before the bone is harvested, the graft can be xed with the implant screw. 358Implant Terminologyeventual screw implant will press the graft onto the area being augmented.Apart from cases of seriously advanced atrophy of the alveolar process in the maxilla and mandi-ble, this augmentation method can also be used after resection of tumors or for genetic defects (eg, cleft lip and palate). It is important to ensure that there is a direct bone contact surface in the augmented area and an adequate blood supply for the graft tissue.Alveolar bone splitting (spreading of the alveo-lar ridge, alveolar extension plasty) is performed in cases with a minimum ridge width of 3 mm (Fig 9-50). An implant bed should be created by driving the alveolar ridge apart horizontally and condensing the cancellous bone in the implant area (Fig 9-51). To do this, the vertical cortical la-mella is separated in the mesiodistal direction with a ne diamond disk and moved apart with a chisel-shaped spreader. In the process, the prac-titioner swivels and turns the spreading instru-ments carefully to and fro, thereby condensing the cancellous bone. Once the depth of the split is adequate for the implant, the implant can be inserted simultaneously or the cavity can be lled with bone/bone replacement material (Fig 9-52).In an alveolar split osteotomy, the collapsed al-veolar process is separated along the course of the dental arch, and a bone segment joined to the periosteum is moved vestibularly by the width of the alveolar ridge and xed. This osteoplasty (segmental bone splitting) is intended to create space for the implant. The cortical bone in turn is vertically split, and a right-angled osteotomy (cutting the bone) is performed mesially and dis-tally to the planned implant extending down to the basal bone. The bone lamellae at the base are then surgically fractured with care and moved transversally. The bone lamellae can be stabi-lized with miniplates. The nourishing periosteum attached to the mobile bone lamellae must be preserved; if not, the bone will be resorbed. The resulting cavity can be lled with bone chips or replacement material.A cavity can be demarcated from the bone with a membrane that is xed precisely to the bone. This cavity is lled with autogenous bone (collect-ed drilling chips) or bone replacement material. After 6 months, the membrane can be removed and the bone surface smoothed. Vertical or trans-verse bone gain of about 3 mm can be achieved.Sinus elevation makes the maxillary sinus smaller or builds up the sinus oor (augmenta-tion). The lateral bony wall of the maxillary sinus is split (osteotomy) just above the alveolar ridge, the periosteum and sinus membrane (Schneide-rian membrane) are raised, the resulting cavity is lled with augmentation material (bone chips and bone substitute), and the cavity is stabilized with a vestibular membrane.If a facial window is cut into the maxillary si-nus, a distance of more than 1 cm from the up-per (crestal) alveolar ridge must be maintained so that the alveolar process does not collapse. If the bone height in the implantation area is still 4 mm, implant placement can be performed simultane-ously. After the operation, nose blowing is not al-lowed for 14 days and nasal drops are prescribed; overseas ights and diving are prohibited for 4 weeks because of the pressure increase involved.In a closed (internal or inner) sinus elevation, the bony bed in the posterior region of the max-illa can be enlarged and condensed by detaching the mucosa from the oor of the maxillary sinus and lling the resulting cavity with bone replace-ment material (Fig 9-53). The implant can be in-serted in the same surgical procedure or implant-ed at a later date once the bone has regrown. This technique does not require lateral access to the maxillary sinus, which is necessary in a sinus oor elevation procedure.For vertical augmentation, the mucosa of the maxillary sinus is raised with a bone condenser without tearing. The implant site is xed with a spherical bur so that a pilot instrument with a small diameter of up to 2 mm can be pushed as far as the sinus oor (Fig 9-54).Increasing sizes of bone condenser are then driven in carefully so that the bone is condensed in a circular and vertical fashion (Fig 9-55). This instrument, which has the same shape and di-mensions as the implant, breaks open the oor of the maxillary sinus (Grünholz fracture) and com-presses the bone chips and the bone replacement material introduced at the same time, while lifting the sinus endothelium by about 3 mm (Fig 9-56). No drilling is involved, but the instrument, in in-creasing diameters, is driven toward the maxil-lary sinus with hammer blows and carries the bone replacement material at its tip (Fig 9-57). In the case of bone condensing, the expansion time needed by the bone must be taken into con- 359Augmentation Methods in ImplantologyFig 9-50 If the width of the alveolar ridge is much narrower than the implant diameter, an implant cavity can only be created by spreading the ridge.Fig 9-51 In alveolar bone splitting, a vertical lamella of cortical bone is split and pushed apart horizontally, and the cancellous bone in the implant area is condensed.Fig 9-52 If the alveolar ridge is suf-ciently spread, the cavity can be lled with bone replacement material, or the implant can be simultaneously inserted.Fig 9-53 A closed sinus elevation can be employed if the alveolar ridge is large enough but the maxillary sinus so extensive that the necessary implant length would extend into the sinus.Fig 9-54 A pilot drill is used to create an implant channel 2 mm in diameter as far as the sinus oor. Fig 9-55 A bone condenser is carefully driven into the pilot drill hole, and the si-nus oor is elevated without tearing.Fig 9-56 The implant bed is widened with a larger-diameter bone condenser, the cancellous bone is condensed, and the sinus oor is elevated by 3 mm.Fig 9-57 An implant with self-tapping threads can be screwed in with a torque-protected ratchet in a single working step. 360Implant Terminologysideration, and the intraosseous blood vessels must not be constricted. The bone replacement material introduced is compressed into the sinus oor with the cancellous bone until the desired implant length relative to the height of the alveo-lar ridge is reached. Figures 9-58 to 9-66 illustrate the procedures for sinus elevation.Vertical alveolar ridge distraction is a method adopted from orthopedics in which a distractor is used to move apart two bone segments sepa-rated by osteotomy. The resulting gap is closed by the formation of new bone. Distraction is applied in cases of severe vertical atrophy of the alveolar ridge when an adequate transverse bony base is still present. Compared with other forms of aug-mentation, distraction involves hardly any bone resorption, no bone graft has to be harvested, and the treatment time is shorter.For distraction osteotomy, the operating eld is exposed by reecting the mucoperiosteal ap vestibularly. The vertical distractor can be tted to the bone in the correct position with suitable bending forceps so that a pilot drill can be used to create the holes for screws that will later x the distractor in place.Osteotomy of the bone segment to be raised is then performed with ne-cutting osteotomy in-struments, for example a diamond cutting disk or jigsaw, and special ne chisels. The distractor in the correct position is then connected to the local bone and mobile bone segment to be lifted, and a distraction gap is left. The operation wound is closed, and the result of the operation is checked by radiograph. The patient can carry out continu-ous distraction himself or herself with a special screwdriver. Implant placement can take place 12 weeks after the desired distraction height has been reached; at that point the distractor is re-moved.Bone substance regenerates very slowly be-cause of its lower metabolic rate. Complete re-generation of bony tissue takes 10 years, com-pared with 6 months for liver cells and 3 days for intestinal epithelium. Synthetic bone replace-ment material, such as tricalcium phosphate, is similar to bone and is used as a spacer in the case of bone defects. The use of foreign material de-lays the regrowth of a person’s own bone but can dene the direction of growth. Bone replacement materials contain vital protein structures, such as bone morphogenetic proteins, which specically stimulate osteoblast formation and hence bone growth (therefore, they are osteoinductive) so that a high-quality implant bed can be formed.Implant positions must be a minimum distance apart to ensure that the bony tissue is properly nourished or to achieve undisturbed osseointe-gration. The minimum distance between implant abutments at the gingival emergence site is 3 mm; the distance from natural neighboring teeth should be a minimum of 1.5 mm.Fig 9-58 A closed sinus elevation can also be performed in a two-stage operation. The implant can be placed after resorp-tion of the replacement bone and regeneration of the implant region. A minimum distance between implant sites is neces-sary for undisturbed osseointegration. 361Augmentation Methods in ImplantologyFig 9-59 In a closed (internal) sinus elevation, an implant chan-nel is milled transcrestally (through the alveolar process) as far as the cortical bone of the maxillary sinus. It can be advanced with conventional bone cutters or by piezoelectric surgery up to about 1 mm before the maxillary sinus.Fig 9-60 The risk of perforating the sinus membrane can be reduced by puncturing the cortical bone with a high-frequency vibrating piezoelectric instrument. The piezoelectric instrument can thus be gently guided against the soft tissue without per-forating the sensitive membrane.Fig 9-61 This mucous membrane is detached from the oor of the maxillary sinus with physiologic saline that is injected under controlled pressure or a uid-lled balloon catheter. The quantity of saline or the volume of the balloon will determine the height to which the mucosa is detached.Fig 9-62 Elevating the oor of the maxillary sinus (ie, sinus elevation or sinus oor augmentation), becomes necessary when the bone supply is insufcient for implant placement because the maxillary sinus is too large, ridge absorption is severe, and short implants are not sufcient to bear the su-perstructure. 362Implant TerminologyFig 9-63 For an external or open sinus elevation, the maxillary sinus is opened with a facial window under general anesthesia. During osteotomy of the bony side wall, the mucosa of the maxillary sinus (sinus membrane) must not be damaged.Fig 9-64 To ensure that the sinus membrane is not perforated during elevation of the sinus oor, piezoelectric instruments are used to lift the soft tissue with high-frequency vibrations (up to 36 kHz). The mucosa is detached from the bone margins with small, replaceable, disk-like preparation attachments.Fig 9-65 The separated bony wall is folded upward and in-ward, and the periosteum and sinus mucosa are carefully de-tached and pushed upward. The resulting cavity is lled with bone chips or bone replacement material under direct vision. The operating eld is then covered with a membrane.Fig 9-66 If the available alveolar bone is stable enough, an im-plant can be inserted immediately, an approach that has proved to be osteoinductive. If not, the implant bed can only be pre-pared and implant placement carried out after an appropriate healing phase (a minimum of 6 months). 363Bone Replacement MaterialsBone Replacement MaterialsBone replacement material is used in sinus oor augmentation and alveolar ridge augmentation or is used to ll local bone defects after bone re-section. The material must be biocompatible and immunologically safe while having a positive (os-teoinductive) effect on bone growth. The follow-ing paragraphs describe different types of bone replacement materials (Fig 9-67).Autogenous bone grafts are pieces of replace-ment bone from one’s own body. They are immu-nologically safe and heal most effectively when close to the donor site from which they are har-vested. As the antigens in autogenous bone are identical to those at the implant site, no rejection reactions will occur. Nevertheless, specically sensitized lymphocytes can form antibodies to the graft if the autogenous implant is obtained from more distant regions of the body.Allogeneic bone grafts come from donors who are not genetically identical to the recipients but belong to the same species, for example human-to-human transmission. Because there is a high risk of infection due to the transfer of pathogens from donor to recipient, allogeneic bone replace-ment materials are not used in implantology today.Xenogeneic bone grafts (or xenografts) come from a different species (eg, cattle, pig) than the recipient. The replacement material is denatured and used as bone chips after laboratory process-ing. The replacement material acts as a spacer and is permeated by osteocytes; it resorbs and attaches to the person’s own bone. The bovine (ie, relating to cows) hydroxyapatite produced at high temperature forms the densest cell structures.Alloplastic bone replacement materials are the synthetic sintered ceramics, such as nonresorb-able hydroxyapatite, resorbable tricalcium phos-phate, and resorbable bioglasses. Mixed prod-ucts comprising hydroxyapatite and tricalcium phosphate are also available.Small defects can be lled with bone replace-ment materials to which autogenous bone chips are added. The best way to make up for large bone defects is with one’s own bone because en-dogenous tissue forms a stable foundation for implants after healing. Narrow, at, atrophied alveolar ridges, for example, are built up by au-togenous bone. The harvested bone blocks are xed with special screws and heal over several months. During the healing phase, the new bone is covered with a membrane.Autogenous From the recipient’s own body; immunologically safe; good healingAlloplastic Synthetic sintered ceramics (hydroxyapatite, tricalcium phosphate) Xenogeneic From a different species; laboratory-processed bone chipsAllogeneic Human-to-human transmission; high risk of infectionBone replacement material For sinus elevation, alveolar ridge augmentation, or lling local bone defects; biocompatible; immunologically safe; osteoinductiveFig 9-67 Types of bone replacement material. 364Implant TerminologyBone defects are classied as space-making or volume-making defects or non–space-making defects depending on their dimensions. In non–space-making defects, autogenous bone in the form of block grafts is the augmentation mate-rial. The ability of osteoblasts surviving in the autogenous bone to form new bone determines the speed of bone repair. Growth-inducing bone proteins (bone morphogenetic protein), which get into the grafting area with the blood, have the same inuence on bone repair.Local donor sites for dental implant placement are the maxillary tuberosity, oblique line, mandib-ular angle, retromolar region, and chin area (Fig 9-68). Remote sites are the iliac crest (bone chips), ribs, or tibia. Cancellous bone without compact bone (cancellous graft) is most suitable as graft material because the loose bone structure heals most effectively. Autogenous bone replacement requires a second operation with all the possible complications and wound healing problems.Healing of a bone replacement fragment starts with initially resorptive processes, followed by repair phases and capillary containment from the surrounding implant bed tissue through to func-tional integration of the graft, which is promoted by load transfer through implants.Remote autogenous bone (eg, from the hip) be-haves like synthetic material and merely acts as a spacer. It forms the scaffold for the formation of new bone and is initially broken down like syn-thetic replacement material before the jawbone can build up new bone. This mechanism arises because every type of tissue needs genetic mes-senger proteins destined for a specic location in the body for its growth; nutrients alone will not result in tissue growth. Grafted bone from a dif-ferent region of the body is decoupled from the localized system of messenger proteins and is therefore resorbed.Fig 9-68 The preferred mandibular donor sites for bone grafts are the symphysis or chin region, the edge of the mandible, and the retromolar region. Grafts can also be harvested from the mandibular angle or the tuberosity region of the maxilla. These local donor sites provide bone fragments with the best healing rate because they are coupled to the localized system of messenger proteins and will not resorb. Autogenous bone from remote areas of the body, such as the iliac crest, are not as well suited for this reason. 365Fig 9-69 The planning of prosthetics or orthodontic projects has always been done with the aid of anatomical casts. For the purpose of treatment planning start-ing from the end product, an anatomical cast can be sawn into small segments (teeth and jaw sections), which are then placed in a planned position. Fig 9-70 In a diagnostic setup, the in-dividual teeth are placed in the normal position in order to show the treatment objective. A setup may also be the work-ing basis for fabricating orthodontic appli-ances.Fig 9-71 The setup of articial teeth on an anatomical cast is intended to show the position of the teeth that will later be replaced. This setup illustrates the shape and position as well as the occlusal rela-tionships of the planned restorative work, from which the position of an implant can be deduced. A setup can be placed in the patient’s mouth as a demonstration model and is synonymous with the term wax-up. In order to check all functional situations in a patient’s mouth, the setup can be converted into acrylic resin and is then called a mock-up.Treatment PlanningTreatment PlanningTreatment planning for extensive dental restor-ative work, especially in implantology, involves analyzing all the treatment measures, identifying their repercussions, and dening the end result of the prosthetic work in relation to the patient’s needs and wishes. In other words, planning for an implant-borne denture starts with a precise depiction of the end product, which the dentist uses to discuss the possibilities and limitations of treatment with the patient.Planning backward from the treatment objec-tive is particularly necessary when preimplant augmentation procedures for building up a suf-cient bone mass become necessary to ensure the prosthetically optimal positioning of the im-plants. Backward planning denotes treatment planning starting from the end product, for which a setup, wax-up, and mock-up serve as the basis of the planning (Figs 9-69 and 9-70).Setup refers to the preparation of a simula-tion model and has become a keyword in vari-ous techniques (Fig 9-71). In orthodontics, a setup model becomes the working basis for producing a positioner. This involves sawing individual teeth or whole jaw sections out of an anatomical cast and moving them to an ideal position. A thermo-formed splint is pulled over this ideal position, with which orthodontic tooth movements can be performed.A setup for diagnostic purposes should repre-sent the ultimate treatment objective and is one of the fundamental working steps in the clini-cal and laboratory procedures of implant pros-thodontics. To achieve this, the articial teeth are set up in the intended position in wax on a model. Such a setup is also known as a wax-up, another keyword. The wax-up, converted into acrylic resin, can be used as a demonstration model and tried in the patient’s mouth before any dental interven-tion has taken place.Mock-up is the term for such a demonstration model, with which all the functional conditions in the patient’s mouth can be checked (Fig 9-72). In addition to a check of esthetic appearance and ac-cessibility to oral hygiene measures, a phonetic check can be carried out to assess the position of 366Implant Terminologythe anterior teeth and decide on denitive solu-tions. For the clinical diagnostic process in im-plantology, this mock-up can be converted into a radiographic template and then into a drill tem-plate (Figs 9-73 and 9-74).ExaminationImplant placement is preceded by a clinical and radiographic examination intended to assess the topographic and anatomical structures (mental foramen, mandibular canal, maxillary sinus) and the bone supply in the implantation area. Radio-graphs of the implantation area show bone height and soft tissue thickness and make it possible to establish implant positions. The choice and num-ber of suitable implants are based on analysis of the bone and the implant position. The exact clini-cal and laboratory procedure can be represented by the example of gap closure in the mandibular posterior region.Anatomical casts that precisely depict all of the anatomical features are placed in an adjustable articulator, and a wax-up is prepared. Prefabri-cated teeth are set up in exact occlusion, and a silicone key is made. The wax-up is removed, and the set-up teeth are created in transparent acrylic so that a radiographic template results; this can later be reworked into the drill template.For a radiologic check of the planned implant positions, measuring spheres are polymerized in place at the tooth positions. These are depicted on the radiograph and enable bone height to be calculated. Metal sleeves can also be polymerized at the ideal implant positions and serve as refer-ence positions on the radiograph. If the sleeves sit directly on the mucosa, mucosal thickness can be identied. This measurement determines whether severely resorbed alveolar ridges need to be augmented.The mucosal thickness over the implantation area can be checked in the mouth with a probe and the relevant thickness transferred to sawn segments of the anatomical cast (Fig 9-75). To this end, the ridge segments at the implantation site are sawn out of the duplicate of the anatomical cast, and the points for measuring the relevant mucosal thickness are marked. Joining the points together shows the available bone supply for im-plant placement (Figs 9-76 to 9-78).Fig 9-72 A mock-up anchored to the residual dentition with clasps provides a preview of the planned end product and guidance for implant positioning.Fig 9-73 The mock-up is converted into a radiographic template by polymeriz-ing geometric reference bodies in place, which are sharply depicted on radiographs and provide an indication of dimensions.Fig 9-74 The setup/mock-up can be con-verted into a drill template by introducing drill sleeves in the precise implant posi-tion and direction. 367Navigated ImplantationNavigated ImplantationComputer-navigated implantology involves the diagnosis and planning of the operating proce-dure on a computer. Three-dimensional images of the individual anatomical tooth and jaw relation-ships also provide information about the quality of the bone, the nerve canal in the mandible, or the dimensions of the maxillary sinuses.For this purpose, computed tomographs (CT scans) or cone beam volumetric imaging (CBVI scans) of the jaws are required, which are then converted into three-dimensional images by spe-cialized computer programs (Fig 9-79). For the tomographic scans (CT/CBVI) a special x-ray or scanning template with a geometric reference body is required, which can be precisely identi-ed on the radiographic image. For this purpose, a diagnostic setup is converted into a radiopaque (not transparent to x-rays) acrylic template, that is, a scanning template that is sharply depicted on the radiograph. A radiopaque Lego brick or ra-diopaque spheres, for instance, can be used as geometric reference bodies.Fig 9-75 If the mucosal thickness has been checked in the mouth with a probe and marked on the model segments, an initial approximation of the bone supply for the implant site can be estimated, and the implant position and direction can also be established.Fig 9-76 If the bony bed has been depicted by marking the mucosal thickness, the implant direction can be transferred to a drill template, and the drill sleeves can be aligned and poly-merized in place. The drill sleeves are referenced to the diam-eter of the system-specic pilot drill and provide instrument guidance during implant placement.Fig 9-77 A wax-up/setup is converted into a scanning tem-plate with geometric reference bodies. The radiopaque scan-ning template and reference bodies are clearly shown on the radiograph.Fig 9-78 The radiograph not only depicts the scanning tem-plate but also provides information about bone thickness and the position of the mandibular canal. The reference bodies serve as a comparative dimension for measuring bone supply. 368Implant TerminologyBy means of the radiographic scan, very de-tailed information about bone density, the po-sition of the nerve canals, and the maxillary si-nuses is obtained. This information facilitates the following:• Detailed virtual planning of a procedure on the computer• Very accurate alignment of the implants• Reduction of the risk of injury to nerve and blood vessel structures• Less invasive surgical implant insertionA virtual simulation is created on the screen, showing the optimal length, diameter, inclina-tion, and position for the implant; what drilling direction and drill depth should be selected; and what the eventual superstructure will look like.The radiopaque scanning template depicts the setup so accurately that precise alignment of the implant relative to the superstructure can be carried out. These data sets can be converted into models of the jaws; they aid in the fabrica-tion of drill templates and can form the basis for computer-aided design of the denture. After virtual implant positioning, the drill templates with the drill sleeves are fabricated by the stereo-lithography process, or the scanning templates are reworked into drill templates (Fig 9-80). The radiopaque reference bodies enable the scanning template to be aligned in the computer-controlled drill stand so that the drill sleeves can be accu-rately positioned.Fig 9-79 Sophisticated computer-aided design/computer-assisted manufacturing (CAD/CAM) systems, such as SICAT three-dimensional software, allow for computer-navigated im-plantation planning and fabrication of drill templates. The image data from the tomographic recordings (CT/CBVI) are imported via a DICOM (digital imaging and communications in medicine; universal le format for transmitting and storing medical data) import. When the CT surface data are linked to the CBVI vol-ume data, both the gingival contour and gingival thickness—as well as the bony bed with the course of blood vessels, cavities, and nerve paths—can be accurately depicted and converted into a computer-generated design proposal. The system sup-plier fabricates a drill template based on the data. (Courtesy of Sirona.)Fig 9-80 Data sets for drill templates can be created on the computer with the CEHA Implant System (C. Hafner/Pforzheim). The CT/CBVI data are generated on the computer and used for the virtual implant positioning. The software for the CEHA Implant System produces drilling instructions for all the implant positions with adjustment instructions for the mill-ing equipment. As a result, the milling spindle can be aligned with point accuracy in the positioner and can be controlled us-ing the software. The reference template for the tomographic images also serves as a reference for merging the data for the drilling instructions. The drill holes for the drill sleeves are placed exactly at the planned position of the eventual implants. After drilling, a sleeve holder is clamped in place and holds the titanium sleeve during polymerization.Reference templatePositioner 369Clinical ImplantationClinical ImplantationEstablishing mucosal thickness or depicting the available bone supply makes it possible to es-tablish the direction of the implant axis. The ra-diographic template can now be converted into a drill template. The measuring spheres or metal sleeves are removed, and the cavities are closed with acrylic. The pilot drill holes are then placed with a milling machine.The drill hole is aligned with the middle of the tooth that is being replaced and with the center of the alveolar ridge or the available bone. The central positioning should permit a large enough implant diameter so that an optimum emergence prole can be created for the molars to allow adequate oral hygiene. The emergence prole signies that the replacement tooth needs to be matched cervically to the implant diameter with-out creating any niches where contaminants can build up.The implant axis can be corrected by the axis of the abutment. Most implant systems offer angled abutments that can be prepared at a later stage. When drilling, it is important to ensure adequate distances between implants and to pay attention to the implant axis, which should run in the mid-dle of the available bone. Both parameters can be checked by pilot holes on the sawn model.Metal sleeves, which are matched precisely to the diameter of the pilot drill or the implant drill, can be polymerized into the correctly positioned drilled shafts. The drill template may be reduced in some circumstances to permit an adequate hole depth for the pilot drill.It must be possible to x the drill template pre-cisely to the neighboring teeth, either with clasps or by intraoral containment of the teeth border-ing the gap; there must be no shift between the model and the intraoral situation. Finally, the drill template is trimmed vestibularly enough to en-sure that a visual eld for the implant site is cre-ated.1. Surgical phase (implant insertion)A system-specic set of instruments, containing everything necessary for the operation, is used for implant insertion. Patients are treated under local anesthesia on an outpatient basis; general anesthesia is rarely indicated. The actual implant insertion involves several steps:1. The incision clearly exposes the operating eld and must later allow for optimum wound clo-sure. The mucosa is rst incised with a scalpel, the periosteum of the alveolar ridge is lifted off, and the mucoperiosteal ap is reected lin-gually and vestibularly (Fig 9-81).2. The implant area is smoothed with a large bone cutter, and soft tissue remnants are re-moved with a bone curette (Fig 9-82). The drill template is then overlaid, and a marking hole is made with a round bur (at 2,000 rpm) (Fig 9-83).3. Preparation of the implant bed with the aid of the drill template starts with making a pilot hole to assess bone quality and establish the implant axis and length (Fig 9-84). This drilling process must be done with external cooling.4. Milling out the implant bed is performed with system-specic rotary instruments. The inter-mittently guided milling processes are con-stantly cooled with physiologic saline. The bone chips are carried away with the cooling uid. The implant bed is prepared in several steps with internally cooled hollow drills in in-creasing diameters (Fig 9-85). The cutters have marking rings to act as depth guides. Drilling or milling is performed at low speeds (approxi-mately 2,000 rpm) to avoid friction heat that would damage tissues (Fig 9-86).5. Dimensionally accurate widening of the im-plant bed can be done with conical or cylindric reamers. This working step can be performed with a hand instrument known as a ratchet.6. In the case of screw implants, a thread can be cut into the milled tunnels with a thread cutter and the implant bed ushed out. Thread cutting is performed with a ratchet.7. Screwing in the screw implant is done at low speed (15 to 20 rpm) without pressure. Cylin-der implants are tapped into place (Fig 9-87).8. A sealing cap is screwed onto the implant (Fig 9-88). The insertion area is covered with the mucoperiosteal ap, and the wound is sutured tension free. A radiographic check is performed once implant insertion is completed (Fig 9-89). 370Implant TerminologyFig 9-81 The operating eld is clearly exposed by incising the mucosa with a scalpel, lifting the periosteum off the al-veolar ridge, and reecting the mucoperi-osteal ap.Fig 9-82 The implant area is smoothed with a large bone cutter, and soft tissue remnants are removed with a bone cu-rette. The drill template is then overlaid.Fig 9-83 A marking hole is rst made with a round bur rotating at a maximum of 2,000 rpm. Guidance is provided via the drill template.Fig 9-84 Preparation of the implant bed starts with the pilot hole, which is made to assess bone quality and establish the implant axis and length. The drill template is intended to provide reliable guidance and must be rmly xed for the purpose.Fig 9-85 The implant bed is prepared with system-specic rotary instruments. The internally cooled hollow drills are intermittently guided and cooled with physiologic saline, which provides the means of removing the bone chips.Fig 9-86 Drilling or milling is performed at low speeds (approximately 2,000 rpm) to ensure that no friction heat will dam-age tissues. In the case of screw im-plants, the thread is cut into the milled tunnels with a hand instrument and the implant bed is ushed out. 371Clinical Implantation2. Surgical phase (implant exposure)In a second operation, the implant is exposed, the closure screw is removed, and a sulcus for-mer (gingival margin molder, healing abutment) is inserted (Fig 9-90). The mucosa over the closure screw can be surgically exposed or excised with a mucosal punch. The mucosa is sutured around the sulcus former, creating tight adaptation of the soft tissue (Figs 9-91 and 9-92).Fig 9-87 A screw implant is screwed in at low speed (15 to 20 rpm) without pressure, usually with a torque-regulated ratchet. Cylinder implants are tapped into place.Fig 9-88 A sealing cap is nally screwed on without pressure and without moving the implant.Fig 9-89 The insertion area is covered with the mucoperiosteal ap, and the wound is sutured without tension. Im-plant insertion is then done under radio-graphic control.Fig 9-90 After an appropriate healing period of about 6 weeks, a second op-eration is performed to expose the im-plant and unscrew the closure screw. The mucosa can be surgically exposed or excised with a mucosal punch.Fig 9-91 A sulcus former (also known as a gingival margin molder or healing abut-ment) is inserted, and the mucosa is su-tured around this sulcus former to create tight adaptation of the soft tissue.Fig 9-92 After the soft tissue heals, a gingival situation should arise that re-sembles the course of the gingiva in natural dentitions; an interdental papilla should be formed that is adapted to the emergence prole of the replacement tooth. 372Implant Terminology3. Clinical phase (impression-taking)Impression-taking and preparation of the work-ing model are performed with system-specic ac-cessories for impression-taking with closed trays (repositioning technique) and impression-taking with open trays (pickup technique) to achieve pre-cise transfer of the implant position to the work-ing model. In the case of one-piece implants, an impression is taken of the abutment and the gin-gival situation in the same way as a normal tooth preparation for crown and partial denture.Taking impressions with closed trays To take the impression, impression abutments are screwed into the implants (Fig 9-93), and impression copings are tted. The impression is Fig 9-93 An impression abutment is screwed onto the implant for the impression-taking. This abutment is shaped so that an impression can be taken of the gingival situation.Fig 9-94 An impression coping is placed on the impression abutment. The coping has retention wings so that it sticks im-movably in the impression material. An impression is taken with a prefabricated tray.Fig 9-95 The impression abutment is unscrewed from the implant, screwed to a model implant, and repositioned into the impression coping.Fig 9-96 First the gingival mask is inject-ed into the impression. Then a one-piece working model is prepared into which the model implant is inserted. The impres-sion abutment is unscrewed so that the precise gingival situation is visible.Fig 9-97 A precise model abutment is screwed on and provides the working basis for fabricating the superstructure. This impression technique is suitable for single parallel implants. 373Clinical Implantationtaken with a prefabricated impression tray. The impression coping remains in the impression material after the impression has been taken (Fig 9-94). The impression posts are unscrewed from the implants and screwed to the model implant. To prepare the model, the impression abutments with screwed-on model implants are repositioned in the impression copings in the impression (Fig 9-95). The impression abutments engage in the grooves of the impression coping.The impression is cast without loosening the impression abutments. It is advisable to prepare a gingival mask that accurately and exibly de-picts the situation of the surrounding gingiva. After the model has set and the impression has been taken off, the impression abutments are unscrewed from the model implants (Fig 9-96). This method is only suitable for roughly parallel implants (Fig 9-97); open trays must be used for divergent implant axes.Taking impressions with open traysA custom tray is necessary for the denitive im-pression of the implant situation where there are divergent implant axes, and this tray must have occlusal openings at the implant positions. The custom tray is fabricated on an anatomi-cal cast that shows the screwed-on impression abutments. The impression abutments must be blocked out with wax for the anatomical impres-sion (Fig 9-98).For the denitive impression, the impression abutments are screwed onto the implant (Fig 9-99). The screw system protrudes occlusally through the custom tray (Fig 9-100). Once the im-pression material has set, the screw connection is detached so that the impression can be taken out of the mouth. The retentive impression abut-ments remain in the impression (Fig 9-101).Fig 9-98 If the implant axes are divergent, a custom tray must be used to take an impression. The custom tray should be prepared on an anatomical cast depicting the impression abutments. The im-pression abutments are generously blocked out.Fig 9-99 An impression abut-ment is again screwed on, using a special screw sys-tem that is provided. Once again the gingival situation is exposed for impression-taking.Fig 9-100 The custom tray has large holes through which the screw system with its divergent implant axes protrudes. The im-pres sion encompasses the screw system.Fig 9-101 A silicone im-pression is taken of the rmly screwed impres-sion abutments and the screw system, with par-ticular care being taken to depict the gingival situa-tion. Once the impression silicone has set, the screw system is detached and the impression removed. The impression abut ment and screw system remain in the impression. 374Implant TerminologyFor model fabrication, the model implants are screwed to the impression abutments (Fig 9-102). It is also advisable to prepare a exible gingival mask because the impression abutments are re-moved after model fabrication, and abutments are mounted (Figs 9-103 and 9-104). If no gingi-val mask is prepared, it might not be possible to attach the abutments. Special plaster cutters are then used to expose the shoulders of the labora-tory implants in the cervical area of the implant neck to allow interference-free seating of the abutment.4. Laboratory phase (superstructure)Most implant systems permit preparation of the abutment. The implant length, implant axis, and gingival contour can be modied with system-specic instrumentation (Figs 9-105 to 9-107). The original wax-up serves as a guide. The silicone key of the wax-up is overlaid so that the axes and lengths of the implants can be adjusted. After modication, the superstructure can be prepared.The screw head and screw channel of the abut-ment must rst be covered or sealed with a re-movable material. The abutments are then isolat-ed, and the crown copings are modeled, invested, cast, nished, and veneered in the customary way. When fabricating the veneers, it is important to ensure that the emergence prole allows good oral hygiene. No niches should arise, and clean-ing possibilities for interdental brushes must be created.For insertion, the abutments are detached from the model implant and tted onto the implant in the mouth with new abutment screws. The crowns are rst xed temporarily. After a follow-up ses-sion, the crowns can be denitively inserted.Implications for dental technologyThere are no essential differences between the fabrication of a superstructure (ie, an implant-supported denture) and a restoration with peri-odontal or mixed support. The difference from fabrication of normal prostheses lies in the fact that system-specic prosthetic accessories for the implants have to be incorporated according to the manufacturer’s instructions. The choice of material should be based on the implant materi-als to avoid a diversity of materials and associ-ated corrosion processes. Abutments can be in-Fig 9-102 The screw system is also de-signed for the model implant, which is then screwed onto the impression abut-ment. A gingival mask is again injected and the impression cast.Fig 9-103 After the cast has set, the screw is loosened, and the impression and impression abutment are removed. A sawn model is not produced, but the exible gingival mask provides guidance for a correct prosthetic emergence pro-le.Fig 9-104 The nished one-piece model with gingival mask and the screwed-on laboratory analogs (model implants) form the working basis for the superstructure. 375Clinical Implantationterpreted as tooth preparations that are covered with single crowns, partial dentures, or partial or complete dentures in the form of overdentures.The superstructure is prepared on laboratory implants (laboratory analog, manipulation im-plant) that are inserted into one-piece working models made of articial stone (Fig 9-108). In the area of the laboratory implants, no sawn sections are created because the gingival region must re-main intact for an emergence prole that allows good periodontal hygiene with a harmonious transition from the crown form to the implant neck and to the interdental papilla (Fig 9-109). The superstructure must satisfy the criteria of statics, esthetics, and periodontal hygiene and must per-mit full masticatory function.Fig 9-105 The abutments are available in different inclinations of axis so that, in common with the rotationally symmetric con-nections between implant body and abutment, it is possible to precisely align the inclination of an abutment with the nished crown. If necessary, most abutments can be suitably reground.Fig 9-106 Modern implant systems have a difference in di-ameter between the implant body and the abutment, which is known as platform switching. The abutment and implant shoulder do not nish ush; the diameter of the abutment is reduced.Fig 9-107 By means of platform switching, the potential microgap to the implant shoulder is moved inward, and the distance from the bone is enlarged; this provides microbial protection to the marginal hard and soft tissue. The polished abutment provides the basis for adapting the soft tissue by means of a basement membrane.Fig 9-108 The superstructure should be fabricated on a one-piece working model with gingival mask. The super-structure must satisfy periodontal hy-giene as well as esthetic and static requirements.Fig 9-109 The emergence prole concerns the harmonious (ie, the esthetic and periodontally hygienic) transition from the abutment to the contour of the denture. A gingival sulcus and, if possible, an interdental papilla should be created, or an inter-dental situation should be created that is easy to keep clean. 376Implant TerminologyThe masticatory forces are transferred directly to the bone via superstructure and implant be-cause the cushioning between implant and bone is absent. The IMZ TwinPlus implant, for exam-ple, has an intramobile cushioning component between abutment and superstructure. The im-plants are more resistant to vertical forces than horizontal forces. Therefore, a primarily vertical direction of force should be ensured.A single implant can be loaded in a similar way to a single-rooted natural tooth. To absorb hori-zontal forces, the restoration must be connected to the natural dentition. The following occlusal criteria apply to osseointegrated prosthetics:• Fully bone-anchored prosthetics are produced in physiologic occlusion with disocclusion in the posterior region on eccentric mandibular move-ments.• Implant-borne complete dentures display bal-anced occlusion.• Anterior partial dentures as far as the canine with mixed support (osseointegrated/periodon-tal) permit group-guided occlusion.• Posterior partial dentures with mixed support (osseointegrated/periodontal) are constructed with anterior canine guidance.An implant-borne complete denture can be re-tained on several implant abutments. In the man-dible, preferably two to four cylinder implants are placed in the section of the alveolar ridge between the two mental foramina. Bar connec-tors, ball retainer clasps, or conical crowns are suitable as mesostructures. The superstructure is shaped as a purely mucosa-borne prosthesis with extended base, functional margins, and reduction needs. The objective is a statically favorable setup of the dentition with balanced occlusion.The implant bars should be placed so that they axially load the implant abutments without long lever arms and so that there is a distance of ap-proximately 2.5 mm between the lower edge of the bar and the alveolar process to create favor-able hygiene conditions. In the case of ball-head abutments, the resilient secondary anchoring parts are polymerized directly into the denture base. In the case of tapered connections, the implant abutments form the subcrowns on which conical coping nished parts are seated; the conical cop-ings are integrated into a model cast framework.Preparation of the crown, partial denture, or model cast frameworks is done on impression copings or on system-specic mesostructures (gold or titanium copings). The framework can be bonded, cemented, or cast onto the mesostruc-tures.If there is a screw connection between meso-structure (occlusally or lingually) and abutment, the screw hole must be kept clear in the frame-work of the superstructure. The lingual screw hole is oriented mesiolingually so that it is easily accessible.Fixed crown or partial denture frameworks are cut back at the gingiva and interdentally to create adequate space for oral hygiene and allow self-cleaning. The transitions between implant and superstructure must be smooth and gap free to avoid providing any sites for accretions.On bar-retained overdentures, the abutments and their gingival borders must be avoided.OverdenturesOverdentures or hybrid dentures (also known as overlay dentures) are removable prostheses that are xed to and supported by natural tooth rem-nants and/or implants with concealed anchoring components (Fig 9-110). A quasi-complete den-ture anchored with resilient telescopic crowns is also classied as a hybrid denture.Hybrid dentures are indicated in severely re-duced partially edentulous dentitions. They are mainly mucosa borne and have base dimen-sions like complete dentures. The anchorage to root preparations, implants, or resilient double crowns provides horizontal positional stability and a better retentive function than with a den-ture that is held to the dental arch by adhesion, cohesion, and suction. To a small extent, peri-odontal support is also achieved, which greatly improves chewing efciency. Overdentures can be designed as a prospective interim solution for severely damaged residual dentitions, allowing for expansion to a complete denture.The considerable positional stability of hybrid dentures can greatly reduce the resorptive pro-cesses affecting the denture-bearing area. For a mucosa-borne hybrid denture, two anchoring ele-ments per jaw are sufcient to ensure retention of 377Overdenturesthe denture. In the maxilla, cumbersome palatal plates can be omitted from the denture base. The overdenture, anchored or supported on implants, does not touch the mucosa and transfers mas-ticatory force via the implants directly into the jawbone. This design is a possible alternative to a xed partial denture, is better for oral hygiene, and requires the same number of supporting im-plants as xed constructions.Which connecting and anchoring elements are used depends on the number and distribution of the implants and abutment teeth and on the rigid-ity of the superstructure. If there are few implants or abutments, connectors with several degrees of freedom should be used, such as resilient bars, ball clasps, and magnets (Figs 9-111 and 9-112). If there is a sufcient number of implants and abut-ment teeth, form-t and force-t rigid anchoring Fig 9-110 Hybrid cover dentures or overdentures are removable prostheses that entirely cover the anchor abutments. Tooth or root preparations as well as im-plants can serve as anchor abutments. The retentive and supporting elements can be rigid or have several degrees of freedom. Here four implants are placed, which are joined together by bars and form a closed support block. The bar sleeves can be given some resilience clearance to dissipate the masticatory load to the mucosa and relieve the im-plant bed.Fig 9-111 Implants can be tted with dif-ferent retentive elements for the remov-able superstructures. In addition to bar attachments, ball clasps can be used ac-cording to the stud-attachment system or magnet connectors as well as telescopic parallel or tapered ttings. Bars, stud at-tachments, and magnets are prefabricat-ed components, but telescopic connec-tions are usually individually fabricated.Fig 9-112 The prefabricated connector called a Locator (Zest) is a two-piece at abutment made of metal. The primary part (A) has a ring-shaped inner and outer groove as well as a central depression. The secondary part (B) bears replaceable retention inserts (C) made of rigid plastic in different color-coded grades of reten-tive force, which engage on the primary part. The primary part of the Locator is available in various heights for different gingival situations.ABCACB 378Implant Terminologyand supporting elements are possible; these dis-tribute forces better because of their primary and secondary splinting effects.Ball clasps can be used as abutments for im-plants and to anchor root crowns. The integration of stud-attachment secondary parts into the den-ture base is technically the same with root crown anchors and implant anchors, for which only one working model with model implants is neces-sary. In order to take an impression of the implant anchors, impression copings are placed on the implant, and the model implants are integrated into the impression. A working model with these model implants can then be produced. Later, stud-attachment matrices can be incorporated into the record base so that interocclusal registration can be performed with support on the implants.Bar attachments are used for implant-borne over-dentures with four or more implants. They are parallel bars that take on not only a retentive but also a supporting function. Bars with a round or oval prole are used when there are two implants in the region of the mandibular canines for a mu-cosa-supported denture, which is able to rotate around an axis of rotation of the resilient bar.Telescopic double crowns provide easy-to-handle denture anchorage, especially for elderly patients. In purely implant-borne constructions, at least four implants are required, and if they are given resilience clearance, the denture is mucosa and implant supported. If conical telescopes are used, the secondarily splinted implants take on the full supporting function.Tapered or parallel-walled primary parts can be individually modeled and cast or milled out of system-specic abutments relative to one path of insertion. These abutments are made of gold, ce-ramic, or titanium. The telescopic secondary parts are fabricated by conventional dental technology methods and integrated into a model cast frame-work.In the case of implant-retained overdentures, magnets are preferably tted onto two implants in the mandible. As magnets are liable to corro-sion in the oral environment, the magnets are encased in a dense titanium housing (eg, Steco-System Technik). The magnets are worked like stud attachments from the dental technology point of view.Therapeutic Concepts Based on Indication ClassesDental implant placement presupposes a need for prosthodontic treatment, and this is based on a systematic diagnosis, starting with the his-tory taking, followed by clinical, functional, and radiologic examination, and continuing through to the development of an overall therapeutic ap-proach. A need for prosthodontic treatment exists when very severe changes in the orofacial system have occurred or are to be expected as a result of tooth loss. The implant-borne or implant-retained denture has the same functions as conventional dentures, namely biomechanical, therapeutic, pro-phylactic, and regulating functions. As well as the lasting functionality and expansion option afford-ed by the prosthetic solution, it is also expected that the use of dental implants will ensure a xed denture that protects the available hard dental tissue or removable dentures that can be stabi-lized and securely anchored.The need for prosthetic treatment can be iden-tied and assessed based on indication classes. Accordingly, six prosthetically determinate indi-cation classes are distinguished (A to F).Single-tooth replacement (class A)A single-tooth implant is indicated for loss of an anterior or posterior tooth when the adjacent teeth are caries free and not worth undergoing coronal restoration, provided jaw growth is completed and the alveolar process is intact (Fig 9-113). This also applies to several adjoining spaces that are to be treated by single-tooth implants. In the max-illa, up to four anterior teeth can be replaced with single-tooth implants; in the mandible, only two implants can be placed anteriorly because of the spatial conditions. A single implant is placed for each missing tooth. Implant size is determined by the amount of available bone, the size of the gap, and the size of the tooth being replaced.The minimum distance from an implant to adja-cent teeth is 1.5 mm, and where there are several missing teeth, the distance between implants is 3 mm; given a standard implant diameter of about 379Therapeutic Concepts Based on Indication Classes4 mm, a gap must have a minimum mesiodistal width of 7 mm (Fig 9-114).Abutments for single-tooth implants must have antirotation protection (Fig 9-115); they should be individualized and adapted to the course of the soft tissue so that the crown margin can be laid into the subgingival area. Metallic or zirconia ce-ramic abutments are available.Restoration of free-end gaps (class B)In this case, a distinction is made between unilat-eral (class B I) and bilateral (class B II) free-end sit-uations as well as between purely implant-borne and tooth/implant-supported dentures. Free-end gaps can be restored with xed or removable Fig 9-113 A class A single-tooth replacement is indicated if the adjacent teeth are not to undergo coronal restoration be-cause they are free of caries and undamaged. For esthetic rea-sons, the abutments should be adapted to the soft tissue contour so that the course of the crown margin runs in the subgingival area. The abutment should be inclined so as to approach the inclination of the axis of the tooth that is being replaced.Fig 9-114 Given a standard implant diameter of 4 mm, the edentulous space must be at least 7 mm wide so that a dis-tance of at least 1.5 mm from the neighboring teeth can be maintained. This is the only way to ensure that the hard and soft tissues can be nourished and an interdental papilla can be formed.Fig 9-115 For single-tooth implants, antirotation protection between the implant body and the abutment is essential. Im-plant length and inclination of axis must be selected so that nerve and vessel channels and cavities are not injured.1.5 mm4 mm7 mm 380Implant Terminologypartial dentures, which are supported solely on implants or via mixed support on teeth, mucosa, and implants. If the residual dentition is caries free, the use of implants avoids or reduces prepa-ration of the teeth for a xed restoration.To determine the number of implants, guide values can be set that relate to the size of the free-end gap and the implant loading. According to these values, an implant should not bear more than one premolar’s width of additional load as well as the single-tooth load (Fig 9-116). Accord-ingly, the following rules apply if any teeth are missing:• If the second and third molars are missing, im-plant placement is not indicated.• If all of the molars are missing, one or two im-plants are required.• If the second premolar and all molars are miss-ing, two or three implants are required (Figs 9-117 to 9-119).• If the premolars and molars are all missing, three implants are required.In the case of xed dentures for free-end gaps, a distinction can be made between a purely implant-borne restoration and hybrid partial den-tures (mixed support on implants and teeth). Be-cause teeth are mobile within the width of the periodontal space, it was previously believed that mixed support on teeth and implants necessitat-ed a compensatory element. However, long-term studies demonstrate comparable retentive strength for healthy periodontium and implants; that is, the survival rate of purely implant-supported partial dentures is roughly as high as for mixed support on implants and healthy abutment peri-odontium.A xed denture for free-end gaps can be cre-ated in the form of an extension partial denture; that is, free-end pontics can be tted. This results in the same static conditions as with cantilever partial dentures that have purely periodontal sup-port. The longer the free-end pontic, the greater the lever effects or torques acting on the partial denture: On free-end loading, the end abutment is pressed into its bony or periodontal bed, while the anterior abutment is lifted out. Therefore, a free-end pontic should not exceed one premolar’s width.The implants are placed so that they stand cen-trally under a replacement tooth in order to cre-ate a cleanable and esthetically satisfactory cervi-cal situation (Figs 9-120 and 9-121). The implants should also stand on the midline of the alveolar ridge—not too far orally because they would crowd the tongue and not too far vestibularly be-cause they would jeopardize esthetics.Fig 9-116 When determining the number of implants, the principle is that an implant may only bear a maximum of one premolar’s width of additional load as well as the single-tooth load. If the free-end gap is to be closed by the second premolar distal, two implants are sufcient.Fig 9-117 Provided the spatial conditions and the size of the bony bed permit, three implants can be placed for a posterior free-end gap for three replacement teeth. 381Therapeutic Concepts Based on Indication Classes1.5 mmFig 9-118 In the mandible, the length and inclination of the implants is determined by the mandibular canal and the mental fora-men. Minimum distances must be maintained between the implants and from the residual teeth, just like the minimum distance from the nerve and vessel channels. The position and shape of the channels are recorded by CT and can be viewed on a monitor. This aids implant planning and the construction or fabrication of precise drill templates.3 mm3 mmFig 9-119 The spatial course of the nerves and vessels in the mandible can be depicted in a two-dimensional radiograph. A normal radiograph here would show the implant in the nerve and vessel pathway to the mental foramen. Safe implant positioning can only be achieved with computer-navigated implant planning. 382Implant TerminologyRestoration of edentulous gaps (class C)The treatment of interdental edentulous gaps is not problematic. Both purely implant-borne and mixed-support dentures are possible. If two or more adjoining teeth are lost, single-tooth im-plants can be placed or implant-supported partial dentures constructed (Fig 9-122). Fixed partial den-tures in large edentulous gaps can be supported with one or two implants at statically favorable positions. As previously mentioned, hybrid (com-bined) partial dentures presuppose intact peri-odontium of the abutment teeth and do not call for implants with cushioning elements.Fig 9-120 If the area of the alveolar ridge is already severely shrunken and the replacement crowns have to be lengthened cervically, the tooth contour and the abutment should be matched to each other. The implant body should be positioned centrally under the replacement tooth. To ensure that the den-tal crown does not have an extreme taper at the neck, a larger implant diameter must be chosen to achieve a favorable emer-gence prole.Fig 9-121 For good periodontal hygiene, it is important to en-sure that the implant body lies subgingivally in the bone. The soft tissue should attach to the abutment and be congruent with the crown margin. The marginal gap between the abut-ment and the implant should lie away from the bony bed.Fig 9-122 Closing edentulous gaps can be done with single-tooth implants or partial dentures, which can be purely implant borne or have mixed (osseous/periodontal) support. Fixed or removable dentures can be implemented. In severely reduced residual denti-tions, hybrid dentures can be fabricated where the anchorage provided by the remaining teeth is supplemented by gap-supporting implants. 383Therapeutic Concepts Based on Indication ClassesRestoration of severely reduced residual dentitions (class D)Based on the Kennedy classication, severely re-duced residual dentitions are those with two or three teeth remaining. The static relationships of this residual dentition are extremely unfavorable. In terms of prosthetic restoration, purely implant-borne restorations (partial dentures) and mixed-support partial dentures or removable hybrid dentures may, in principle, be considered. Where-as at least eight abutments in a statically favor-able position are necessary for a xed restoration in the maxilla, only six abutments are needed for the mandible. In this situation, one abutment cor-responds to one tooth or implant. In the case of removable prosthetics, six abutments (maxilla) and four abutments (mandible) are sufcient in statically favorable positions (Fig 9-123). A stati-cally favorable position exists if a minimum of two abutments are available in each quadrant.Removable partial dentures are generally used to restore severely reduced residual dentitions. They are anchored to the remaining teeth via clasping or hybrid prosthetic retentive elements, such as double crowns, attachments, or studs. The static relationships in the case of partial den-tures show the correlation between the number of anchoring abutments and the life span of the restoration. Just a small number of implants at statically favorable positions can greatly increase wearing comfort, security of retention, and the life span of a partial denture. If the residual den-tition is distributed in a statically favorable way, the number of necessary implants is reduced; a statically unfavorable residual dentition increases the number of required implants. Retention can be achieved with telescopic components, such as double crowns, attachments, or, in the case of im-plant abutments, ball retainer clasps. Fixed con-structions can work as combined partial dentures, depending on the abutment distribution, where the remaining free-end situations can be restored with extension partial dentures.Restoration of edentulous arches (class E)The maxilla and mandible have differing bone quality and denture-bearing areas of different siz-es, which is why they need to be viewed separate-ly. Restoration of the edentulous maxilla (class E I) can be achieved with removable or xed replace-ments. At least six implant abutments are neces-sary for removable constructions. The implants should be primarily or secondarily splinted in or-der to distribute transverse loads to a resistance block. For secondary splinting, double crowns are appropriate; primary splinting is achieved via bar attachments. Splinting structures call for frame-work reinforcement in removable dentures.If a xed partial denture is to be fabricated for an edentulous maxilla, at least eight implants should be planned for support. Even given minimal atro-phy of the maxilla, it may be practical to design a partly removable partial denture, especially if mu-cosal parts need to be replaced for esthetic rea-sons and for unimpeded phonetics. If the maxilla is so severely atrophied that hard and soft tissues Fig 9-123 A severely reduced partially edentulous dentition can be remedied with a removable denture supported solely on implants if the remaining teeth can no longer be used as anchoring abutments. 384Implant Terminologyhave to be prosthetically replaced, removable overdentures should always be preferred to xed partial dentures in terms of hygiene, phonetics, and esthetics.Restoration of an edentulous mandible (class E II) can be achieved with overdentures (Fig 9-124) or with removable or xed partial dentures. The classic case is the minimal implantology solution with two implants in the position of the canines. The implants can be primarily or secondarily splinted and crucially serve to anchor a mucosa-borne prosthesis. Because such a denture will sink distally on masticatory loading, the denture must not be secured via rigid anchoring elements but rather with ball-head connections, a resilient bar, or a resilient bar attachment.If a removable implant-borne construction is envisaged, four to six implants are necessary; the distal extension should be kept short and should end at the rst molar. The implants should be placed in the region of the mandibular lateral inci-sors and the rst premolars. Six implants in stati-cally favorable positions on a slightly atrophied jaw can also receive a purely implant-borne exten-sion partial denture. In the case of severe atrophy, a removable overdenture is preferable because of esthetics and functional hygiene problems.Restoration of defects (class F)Implants are also used in defect prosthodontics. Here a distinction is made between intraoral and extraoral defect restoration. Intraoral defect res-toration becomes necessary after trauma-related, tumor-induced, or congenital (inborn) defects and can be achieved with xed or removable solutions. Extraoral defect restoration serves to anchor ep-itheses, which are usually designed to be remov-able via studs, bars, or magnets.Design Guidelines for SuperstructuresImplant-supported dentures should be fabricated just like removable or xed prosthodontics. The demands in terms of function, phonetics, and es-thetics are the same as those that apply to con-ventional dentures. Special requirements should be laid down with regard to the accuracy of t of the superstructure on the abutments (tension-free seating), the bonding system between ve-neer material and framework, the accessibility of Fig 9-124 An edentulous mandible can be restored with an overdenture that is supported on four bar-connected implants. The dentition is not entirely replaced; usually the second mo-lars are omitted to reduce tipping stresses. 385Summarythe denture to hygiene measures, occlusal abra-sion resistance, and stability under permanent loading.Careful implant planning with diagnostic wax-up and radiodiagnostics becomes necessary be-cause the implant position and implant diameter can inuence the positioning of the replacement teeth, esthetic impression, and functioning of the superstructure. Both implant position and implant axis should be established during this diagnostic planning process. If there is a major discrepancy between implant position and replacement tooth, a removable overdenture can be used to conceal the implant and support the lips or cheeks.Angled or customized abutments cannot correct an incorrect implant position: however, angled abutments compensate for an adverse implant axis, thereby improving spatial relationships with respect to the replacement teeth and also ensur-ing the bonding of several implants and natural abutment teeth.The dimensions of frameworks for the super-structure are designed to ensure adequate sta-bility in order to tolerate permanent loading and facilitate esthetic veneering or tooth xation without having to overcontour the veneer. Gener-ally speaking, both the materials (nonprecious or precious metal alloys) and the dimensional mea-surements for the xed or removable periodon-tally supported denture can be carried over to the design of superstructures. Bonding technologies, such as cementing attachment parts to an individ-ually cast framework, can also be adopted.One-piece casting for fabricating frameworks offers adequate processing safety and physical ma-terial qualities. Computer-aided design/computer-assisted manufacturing (CAD/CAM) techniques, in which metal frameworks are milled out of a sin-gle piece, provide better accuracy of t than cast frameworks but require high metal consumption. As of 2012, additive methods, in which the frame-work material is applied step by step, are not yet sufciently developed for metallic and ceramic materials.Severe ridge resorption in the area of the miss-ing teeth makes it necessary to replace gingiva and bone tissue. A decision needs to be made as to whether a xed partial denture or a remov-able (over)denture should be fabricated. The ac-cessibility of a removable prosthesis to hygiene measures may have to be set against the needs of the patient, especially when a short upper lip would make the marginal contour of a xed par-tial denture visible relative to the ridge contour. The esthetic requirements can be fullled more effectively by a hybrid prosthesis that reproduces the gingival contour by means of a denture base.Whether primary or secondary splinting is chosen is a design decision, because removable partial dentures or hybrid prostheses can splint the implants together. Primary splinting can be planned that involves bars on which the restora-tion rests, or secondary splinting can be achieved via a rigid denture or partial denture framework. Secondary splinting can only be implemented with rigid anchoring components, namely with double crowns or telescopic parallel ttings; stud attachments or magnetic connections do not of-fer rigid splinting. Fixed superstructures that are rigidly cemented or screwed onto the implants always provide a primary splinting function. If no splinting is to be carried out, one implant must be inserted for each tooth being replaced.Mixed-support removable hybrid dentures rest on implants and the mucosa. An overdenture sup-ported on at least four implants can be combined with resilient anchoring components, enabling the denture to move against the mucosa. An overdenture anchored with two implants can be retained via a resilient bar or studs or magnets, between which one axis of rotation runs; the den-ture rotates around this axis against the mucosa.SummaryFigure 9-125 outlines the clinical and laboratory procedures for dental implant placement. 386Implant TerminologyModel fabrication• Wax-up fabrication• Bite plateSaw model segments• Mark the mucosal thickness• Fabricate a bite plate on the model of mucosal thicknessFabrication of a radiographic templateFabrication of the working model with gingival maskPreparation of the superstructure• Fabricate the framework (using system-specic seminished parts)• Fabricate the try-in• CompletionReworking of the radiographic template into a drill template with positionerFabrication of a custom impression tray • Make perforations for the pickup technique or a closed tray for the repositioning techniqueImpression-taking (pickup technique)• Fit the impression abutments and screw system• Inject around the impression abutments• Take an impression with a custom tray• Unscrew the impression abutmentsExposure operation and impression of implant abutments• Insert the gingival margin molderImplant placement• Analgesia: local anesthesia, endotracheal anesthesia• Implant bed preparation• Implant insertion• Implant closureHistory taking• Record the ndings (diagnosis) and plan the treatment• Inform the patient of operation risks, affordability, alternatives• Take an anatomical impression• Probe the mucosal thicknessPreprosthetic measures, augmentation• Alveolar ridge augmentation• Bone condensing• Split osteotomy• Sinus elevationInterocclusal registration• Wax-up try-in• Corrections• Imaging: CT scans or CBVIInsertion of the superstructure• Screw in the construction or temporarily x/cement it in placeClinical LaboratoryFig 9-125 Procedures for dental implant placement. 387AAbutment(s)angled, 385for implants. See Implant(s), abutment and.for partial dentures, 88–91Abutment teethanchoring of, 83–84definition of, 81loading of, 99, 103periodontium of, 83pontics on, 84, 85f, 101, 102fposition of, 103root shape of, 83, 84froot surface area of, 84, 84fselection of, 85fAbutment-pin implants, 347–348, 348fAccuracy of fitfor complete dentures, 285for conical crowns, 147for crowns, 20f, 39, 147Acid etching, 15, 345Acrylic resin frameworks, for partial dentures, 116Acrylic resin jacket crowns, 51, 53, 53f–54f, 79Acrylic resin plate, 112Acrylic resin veneer crownsas partial denture abutments, 88, 90, 96description of, 60–61, 60f–62fAction levers, 226Active retention accessories, 158, 159fAdhesion, 285Adhesive cone, 144Adhesive forces, 143, 143fAdhesive retention, of bonded partial dentures, 92Akers clasp, 203Allogeneic bone grafts, 363Alternating interdental insertion prostheses, 110Aluminum oxide ceramics, 347Alveolar bone splitting, 358, 359fAlveolar ridgeatrophied, static relationships in, 255faugmentation of, using bone or onlay grafts for, 357–358, 363–364distraction of, 360edentulous, 247of posterior teeth, 246resorption of, 385shrinkage of, 245–247, 246f, 255fsplitting of, 358, 359fvestibular inclination of, 245fAlveolar split osteotomy, 358Amalgam restorations, 10, 10fAnchor(s)clasp, 125for removable partial dentures, 96root crown, 162, 163fAnchoring and supporting elementsclaspsarm length of, 200–201, 202fcast. See Cast clasps.definition of, 181double-arm, 182, 183f–184f, 185, 203lingual arm of, 182, 193fperiodontal hygiene with, 189problem areas with, 189spring deflection of, 182, 192, 194, 199, 201–202types of, 181wrought-wire, 183–185, 184fon overdentures, 377f, 377–378, 385partial denture statics and, 233ffor removable partial dentures. See Removable partial dentures, anchoring and supporting elements for.telescopic. See Telescopic anchoring and supporting elements.Anchoring band crown, 136Anchoring crowns, 21Angled abutments, 385Antagonistscrown surfaces adapted to, 17, 19fdescription of, 1–2, 2fsupereruption of, 86Anterior interdental insertion partial dentures, 110Anterior jaw joint, 298Anterior palatal strap, 120, 121fAnterior partial dentures, 376Anterior teethapproximal contacts on, 70f, 71in complete dentures, 272–278, 273f–278flingual surfaces on, 69–71, 70fAPFNT system, 322f–323f, 322–324Approximal contacts, 70f, 71Articulated coupling, of removable partial dentures with residual dentition, 126, 128fIndexPage numbers followed by “f” denote figures, and those followed by “t” denote tables. 388IndexAArticulation, 298Articulation theory (Gysi’s), 292, 296ArticulatorsGysi’s working method, 293–295, 294fmodel adjustment on, 328fAtrophy of disuse, 243Attraction forces, 214Autogenous bone grafts, 363, 363fAutogenous implants, 342BBack-action clasp, 204, 205fBackward planning, 365Balanced articulation, 294, 294fBall clasps, 378Ball-head clasps, 184f, 185Banded crowns, 48–49, 50fBar attachments, 378Bar joints, 156Bars, 156–157, 156f–157fBearings, 215, 215fBennett angle, 293Bennett side shift, 256, 257fBilabial sounds, 260f, 261Bilateral interdental insertion partial denture, 87, 110Biologic prostheticschewing cycle, 314–315definition of, 313Physiodens teeth, 316, 316f–317fprinciples of, 313–314tooth setup in, 315–316, 316f–317fBiomechanical function, of dental prostheses, 6, 7fBiostatic balance, 108fBlack’s classification, of caries, 8, 9fBlade implants, 347, 348fBonded attachments, 92Bonded partial dentures, 90–92, 91fBone condensing, 358, 360Bone graftsallogeneic, 363alveolar ridge augmentation using, 357–358, 363–364autogenous, 363, 363fdonor sites for, 364, 364fxenogeneic, 363Bone morphogenetic proteins, 364Bone-supported tooth restorations, 110Bonwill circle, 266, 273, 273f, 275Bonwill clasp, 204, 205f, 228f, 234Bonwill triangle point, 293Bonyhard clasp, 185, 204, 205fBuccinator pockets, 290CCalcium phosphate ceramics, 347Calottes, 301, 301fCamper plane, 315Canine guidance, 268Canines, in complete denturemandibular, 274–275maxillary, 277, 277fCantilever partial denture, 88, 88fCantilever pontics, 101, 101f–102fCaries, 8, 9fCast clasps, 125activation of, 187, 189advantages of, 186, 187fclasp arms of, 185on coronal restorations, 208, 209fdesign of, 185, 186f, 203–207, 204f–207fdisadvantages of, 186, 187ffunction of, 191occlusal rests of, 189–191, 190f–191f, 203, 223problem areas with, 189requirements for, 187–189, 188f, 192–193retentive force ofdetermining of, 196–198, 197fequation for, 198requirements, 191–193, 192fspring force versus, 196surveying casts to determine, 198–200, 199f–200fspring force of, 194–195, 195fstatically indeterminate systems created with, 223Cast-clasp denture, 234–235, 238Casting on, 169, 177fCastspositions of, 198, 199fsurveying, 198–200, 199f–200fCavity floor, 8Cavity margin, 8Cavity preparation, for restorations, 8, 9fCavity walls, 8, 10fC-clasps, 183f, 185Central incisors, in complete denturemandibular, 274, 274fmaxillary, 275–277, 276fCentric occlusion, 217, 295f, 314Ceramic(s)aluminum oxide, 347calcium phosphate, 347composition of, 63, 63fCeramic crowns, 55f–57f, 55–58Ceramic veneering, 178f–179fCeramic veneersas partial denture abutments, 88–89description of, 63f–65f, 63–66Ceramic-fused-to-metal crowns, 66–69Ceramic-veneered pontics, 92Cerestore, 56Chamfer preparationfor ceramic-fused-to-metal crowns, 67, 68fdescription of, 30, 30f, 33Chamfer/shoulder preparation marginfor ceramic-fused-to-metal crowns, 66, 68fdescription of, 30f, 31Channel-shoulder-pin milling, 136, 137fChannel-shoulder-pin retention, of partial crowns, 73–75, 74f–75fChewing cyclebiologic prosthetics and, 314–315Gerber’s description of, 306Gysi’s description of, 292, 292fChewing impression, 249Christensen phenomenon, 256–257, 256f–257f, 294Circular notch with shear distributor, 164t–165tCircumferential clasps, 205Clasp(s)arm length of, 200–201, 202fback-action, 204, 205fball, 378Bonwill, 204, 205fcast. See Cast clasps.circumferential, 205definition of, 181A 389CIndexdouble-arm. See Double-arm clasps.lingual arm of, 182, 193fNey, 203, 204f–207fperiodontal hygiene with, 189problem areas with, 189split, 204, 205fspring deflection of, 182, 192, 194, 199, 201–202types of, 181wrought-wire, 183–185, 184fClasp anchors, 125Clasp lines, 223, 227Clasp stem arrangement, 115Clasp survey line, 182, 198Class I caries, 8, 9fClass II caries, 8, 9fClass III caries, 8, 9fClass IV caries, 8, 9fClass V caries, 8, 9fClearance fit, 131–133Closed implants, 335Closed-mouth impression, 249Closed-saddle framework, 115, 115fClosed-tray impressions, 372f, 372–373Cohesion, 285Collar crowns, 48–49, 50fCompensating curves, 257, 258f, 266, 279, 298Complete denturesaccuracy of fit, 285alveolar ridge shrinkage, 245–247, 246fAPFNT system, 322f–323f, 322–324artificial teeth foranterior teeth, 269, 272–278, 273f–278fAPFNT system setup, 322f–323f, 322–324biologic prosthetics setup of, 315–316, 316f–317fdesign of, 258–259, 259fGerber’s setup instructions, 312–313, 313fGysi’s setup instructions, 296, 297fHiltebrandt’s setup instructions, 299flateral movements of, 269, 271fLudwig setup, 321fmandibular anterior teeth, 272–275, 273f–275f, 329fmandibular canines, 274–275mandibular central incisors, 274, 274fmandibular molars, 279f, 279–280mandibular posterior teeth, 278–280, 279f–281f, 332fmandibular premolars, 280, 280f, 332fmaxillary anterior teeth, 269, 275–278, 276f–278f, 330fmaxillary canines, 277, 277fmaxillary central incisors, 275–277, 276fmaxillary lateral incisors, 276f, 277maxillary molars, 281, 284maxillary posterior teeth, 281f–283f, 281–284, 332fmaxillary premolars, 281, 332focclusal plane and, 256–258, 256f–258fphonetics affected by position of, 260f–261f, 261positioning of, ways to check, 269–272, 270f–272fposterior teeth, 278–284, 279f–283f, 332fprotrusive movements of, 269setup of, 251–253balanced muscle tone for, 290, 290fbaseextension options, 288–291, 289f–291fillustration of, 260fnonhardening, 320, 321fbiologic prosthetics. See Biologic prosthetics.body ofdesign of, 289f–290fwax-up, 333fbuccinator pockets, 290in canine region, 311–312, 312fdefinition of, 6edentulous jawimpression-taking of, 247–249, 248fmandible, 264–266, 265f–266fmaxilla, 262–263, 262f–263fmodel analysis of, 262–266, 326f–327fextension options, 288–291, 289f–291ffabrication of, 242interocclusal registration, 249–251, 250f–251f, 325fLudwig technique for, 318–321, 318f–321fmandibular anterior teeth setup, 329fmandibular premolars, 331fmaxillary anterior teeth setup, 330fmaxillary premolars, 331fmodel adjustment in articulator, 328fmodel analyses, 326f–327fposterior teeth, 332fwax-up of denture body, 333fworking steps involved in, 324, 325f–333fFehr’s working method, 301, 301fGerber’s working methodchewing cycle, 306Condylator, 307f–309f, 307–310Condyloform teeth, 308–310, 309f–310fmandibular movements, 306masticatory stability, 310–312, 311f–312fprinciples of, 306–307Gysi’s working methodarticulators, 293–295, 294fchewing cycle, 292, 292fcondylar path, 296mandibular movement, 293, 293foverview of, 292–293setup instructions, 296, 297fHaller’s working method, 300f, 300–301, 311Hiltebrandt’s working method, 298–299, 299fimplant-borne, 376impressions foredentulous jaw, 247–249, 248fin Ludwig technique, 318, 318f–319fJüde’s working method, 304–305, 305fmandibular movements, 293, 293f, 298mechanical retentions for, 285–286, 286fmodel analysis formandible, 264–266, 265f–266f, 327fmaxilla, 262–263, 262f–263f, 326f 390IndexCmucosa-borne, 221orientation guides and measures, 251, 252foverjet, 270, 270f, 282f–283f, 316overview of, 241–243, 242fretention of, 284–286, 285fretentive force of, 291, 291fSchreinemakers’s working method, 302, 303fsetupAPFNT system, 322f–323f, 322–324in biologic prosthetics, 315–316, 316f–317fGerber’s instructions, 312–313, 313fGysi’s instructions, 296, 297fHiltebrandt’s instructions, 299fLudwig technique, 321frules for, 266–268statics of, 253–258, 253f–258fsuction effect, 286–288, 289f–291ftooth loss, anatomical changes after, 243–245Uhlig’s working method, 304valve-type margin of, 287, 288fworkflow for, 242fComposite restorationsdescription of, 10–11, 11finlays, 12Computed tomography, 367Computer-aided design/computer-assisted manufacturing, 58, 368f, 385Computer-navigated implantology, 367–368, 368fCondylar guidance, 3Condylator, 307f–309f, 307–310Condyloform teeth, 308–310, 309f–310fConesurfaces of, 142f, 142–143types of, 144, 144fCone beam volumetric imaging, 367Conical crownsaccuracy of fit, 147adhesive forces, 143, 143fcharacteristics of, 164t–165tdefinition of, 142design of, 236disadvantages of, 146–147fabrication of, 146groups of, 146primary part of, 142secondary part of, 142static friction, 142f, 143taper angle of, 142–144, 144fConical fittingsassembly of, 146fdescription of, 131disadvantages of, 147illustration of, 131f, 134fpractical value of, 145–147Conical post, 76, 77fContact osteogenesis, 341, 341f, 343f, 344Continuous partial denture, 87Core buildup, for onlays and overlays, 14Coronal restorationscast clasps on, 208, 209fcontraindications for, 23crowns. See Crown(s).indications for, 22–23masticatory system affected by, 22oral hygiene considerations, 23Corrosion, 342–343Cost-effectiveness analysis, 232Crossbite position, 255, 294, 311Crown(s)accuracy of fit for, 20f, 39, 147acrylic resin jacket, 51, 53, 53f–54f, 79anchoring, 21banded, 48–49, 50fceramic, 55f–57f, 55–58classification of, 21f–22f, 21–22collaborative teamwork involved in fabricating, 23collar, 48–49, 50fcomputer-aided design/computer-assisted manufacturing applications, 58conical. See Conical crowns.definition of, 6full. See Full crowns.functions of, 17–21, 19f–20fimpressions for, 33–36, 33f–37fjacket, 51–54, 52f–53fmargin of, 26–27, 37–39materials used to create, 22metal-ceramic, 65occlusal surfaces of, 17, 19fpartial. See Partial crowns.porcelain, 55, 56fpost, 18f, 22, 22fpost and core, 75, 76f, 78, 78fon posterior teeth, 69–70, 70fprefabricated, 48protective, 21, 21freplacement, 21retention of, 21fsupportive, 21surface curvature of, 19, 19f–20ftelescopic. See Telescopic crowns.tooth preparation forapproximal surfaces, 31, 31fbuccal surface preparation, 32chamfer, 30, 30f, 33chamfer/shoulder, 30f, 31, 66, 68fcharacteristics of, 24conical, 24, 24f, 52fcrown margin, 26–27, 37–39cusp bevel, 32–33cylindric, 24, 24f–25fdepth marking, 31finish line, 32f, 33goals of, 24impressions after, 33–36, 33f–37finstruments used in, 31marginal periodontium affected by, 37–39occlusal surface preparation, 32, 32foral surface preparation, 32phases of, 31–33, 31f–33fpreparation margin. See Preparation margin.reasons for, 23–24shoulder, 28–30, 29f–30f, 33, 38f, 52fsurface smoothing, 32f, 33tangential, 27–28, 33, 38fwater cooling during, 31, 31fveneer. See Veneer crowns.vertical curvature characteristics of, 19fCrown margin, 26–27, 37–39defective shaping of, 38f, 39overhang of, 38f, 39in shoulder preparation, 38f, 39in tangential preparation, 38f, 39Curve of Spee, 258f, 293Cusp bevel, 32–33 391FIndexCustom-tray impression, 248Cylinder implants, 347, 348fCylindric fit, 134, 134fCylindric form, of manually fabricated attachment, 136, 136fCylindric post, 77, 77fCylindric tooth preparationdescription of, 24, 24f–25ffor full crowns, 73DDegussa multi-CON system, 160f, 160–161, 164t–165tDelayed implant placement, 337, 355Density, 214Dental archesclassification of, 106, 108fKennedy topographic classification of, 106partially edentulous, 105, 106f–109fDental prostheses. See Prostheses, dental.Dentition. See also Teeth.removable partial denture coupling with, 126–128, 127fresidual. See Residual dentition.Denturescomplete. See Complete dentures.fixed implant-supported, 337fixed partial. See Fixed partial dentures.hybrid, 376, 377foverdentures, 155, 155f, 376–378, 377fpartial. See Partial dentures.removable partial. See Removable partial dentures.telescopic crowns for anchorage of, 378Design planning, of partial dentures, 230–232Devitalized teeth, 75, 75fDicor technique, 58Disc dislocation, 3Distal tipping, 198, 199fDistance osteogenesis, 341, 341f, 343f, 344Distobuccal cusp, 45f–46fDistolingual cusp, 47fDistraction osteotomy, 360Dolder bar, 155, 155fDolder bar joint, 156, 161Double-arm claspsBonwill clasp, 204, 205fdescription of, 182, 183f–184f, 185, 203modifications of, 204, 205fwith occlusal rest, 203split clasp, 204, 205fDouble-crescent clasp, 184fDouble-mix impression, 34, 35Dovetail attachment, 160, 161fDowel crowns, 78Drop clasps, 184f, 185Dysgnathic bite relationships, 69, 70fEEccentric forces, 213fEdentulism, complete, 4, 4fEdentulous arches, 383–384, 384fEdentulous gapsfixed partial dentures for, 382, 382fsingle-tooth implants for, 382, 382fEdentulous jawImpression-taking of, 247–249, 248fmandible, 264–266, 265f–266fmaxilla, 262–263, 262f–263fEdentulous spacesdefinition of, 105dental arch affected by, 1, 2fenlargement of, 2fixed partial dentures for, 83fKennedy topographic classification of, 107ftooth migration into, 1, 2fEichner classification, 106–107, 109fElastic limit, 194Electroformed inlays, 12Elongation of teeth, 2, 2fEncircling catchdefinition of, 136–137error analysis of, 139, 139fillustration of, 137fwith shear distributors, 137f, 137–139Endosseous implantscomponents of, 336f, 349fdefinition of, 340design of, 349–351, 349f–351findications for, 337mini-implants, 355–357, 356fplacement of, 340, 340ftypes of, 347–348, 348fEndosseous-subperiosteal implants, 340, 340fEngineering, 211Equilibriumdefinition of, 211types of, 215FFacial appearance, edentulism effects on, 4, 4fFacial expression, 1Facings. See Veneer(s).Fehr’s working method, 301, 301fFeldspar, 63Firing, of ceramics, 64f, 65Fittingsconical, 131, 131fdefinition of, 129industrially fabricated attachment, 148, 149fmanually fabricated attachment, 136f–137f, 136–138parallel. See Parallel fittings.precision, 129–131, 130fprimary part of, 129–130, 130fsecondary part of, 129–130, 130fFixed partial dentures. See also Partial dentures.cantilever, 112, 126categorization of, 92, 93ffor ceramic veneers, 67fdefinition of, 6design of, 92disadvantages of, 96for edentulous gaps, 382, 382ffor edentulous spaces, 83ffor free-end gaps, 380hygiene issues with, 87for interdental gaps, 240multispan terminal, 87, 88fremovable partial dentures versus, 86f, 87veneer thickness for, 67fFloating bearing, 215FM hinge joint, 161, 161fForce(s)definition of, 211 392IndexFeccentric, 213ffriction, 220horizontal, 218fline of action for, 212fparallelogram of, 212on residual dentition, 217–218sagittal, 217unit of, 211, 214vertical masticatory, 218Force couple, 213Foreign body irritation, of marginal periodontium, 37–39Four-fifths crown, 18f, 71, 72fFrameworkacrylic resin, 116for ceramic-fused-to-metal crowns, 66–69closed-saddle, 115, 115ffor partial dentures, 116–117, 117f, 376for removable partial dentures. See Removable partial dentures, frameworks for.for veneer crowns, 59–60, 59f–60f, 62fFree-end denture, 228fFree-end gapsdescription of, 105fixed partial dentures for, 380implants for restoration of, 379–380, 380f–382fFree-end saddlesclasp denture for, 222fdescription of, 114, 127f–128f, 154, 157f, 218design principles for, 227movements of, 222fperiodontal support of, 223–225, 223f–225fsinking of, 226stress on, 237Fricatives, 261, 261fFriction, 219–220Friction coefficient, 220Friction forces, 196, 197fFrontal interdental insertion partial denture, 87Full crownsas partial denture abutments, 88casting of, 48cylindric tooth preparation for, 73definition of, 39description of, 18f, 21, 21ffinishing of, 48full-cast crowns, 40–48, 41f–47ffull-metal crowns, 23, 88, 209fjacket crowns, 51–54, 52f–53focclusal surface of, 42f–47f, 43prefabricated attachment fittings used with, 150tooth retention of, 39veneer crowns. See Veneer crowns.wax-up technique for, 40–41, 41f–42fFull-body implants, 349Functional disordersdefinition of, 1residual dentition loading and, 4–5GGalvano gold coping, 58G-clasps, 184f, 185Genioglossus muscle, 305Gerber retention cylinder, 162Gilmore clip system, 156Gingival preparation margin, 26fGlass-ionomer cement restorations, 11Glottal stops, 260f, 261Glycoproteins, 341Gold compaction restorations, 11, 11fGothic arch tracing, 250, 319Gravitational forces, 214Gysi’s working method, for complete denturesarticulators, 293–295, 294fchewing cycle, 292, 292fcondylar path, 296mandibular movement, 293, 293foverview of, 292–293setup instructions, 296, 297fHHalf-crown, 18f, 71, 72fHaller molars, 300Haller’s working method, 300f, 300–301, 311Hiltebrandt’s mortar-and-pestle tooth, 259, 308Hiltebrandt’s working method, 298–299, 299f, 311Hinge joints, 157, 157fHollow-body implants, 349Hollow-cylinder implants, 347, 348fHooke’s law, 219Horseshoe connector, 120, 121fHorseshoe form, of manually fabricated attachment, 136, 136fHybrid dentures, 376, 377fHygienic partial denture, 93fHygienic pontic, 94IImmediate implant placement, 337, 355, 356fImmediate prosthesis, 6Implant(s)abutment andangled, 385antirotation protection, 351connection between, 350f, 350–353external connection between, 352, 352ffabrication of, 374, 375fillustration of, 336f, 350finternal connection between, 352, 353fminimum distance for, 360, 378screw connection between, 376superstructures screwed onto, 353, 354fabutment-pin, 347–348, 348falveolar ridge augmentation using bone or onlay grafts for, 357–358, 363–364anchorage by, 114augmentation methods foralveolar bone splitting, 358, 359falveolar ridge, using bone or onlay grafts, 357–358, 363–364alveolar ridge distraction, 360alveolar split osteotomy, 358bone replacement materials used with, 363–364, 363f–364fsinus elevation, 358–360, 359f–362fautogenous, 342blade, 347, 348fbone quality considerations for, 338bone reaction to, 341, 341fclosed, 335contraindications for, 337–339, 338f 393IndexIcylinder, 347, 348fdefinition of, 335delayed placement of, 337, 355edentulous arches restored with, 383–384, 384fedentulous gaps restored with, 382, 382fendosseouscomponents of, 336f, 349fdefinition of, 340design of, 349–351, 349f–351findications for, 337mini-implants, 355–357, 356fplacement of, 340, 340ftypes of, 347–348, 348fendosseous-subperiosteal, 340, 340fendostructure of, 339exostructure of, 339exposure of, 371, 371ffree-end gaps restored with, 379–380, 380f–382ffull-body, 349healing of, 341f, 341–342hollow-body, 349hollow-cylinder, 347, 348fimmediate placement of, 337, 355, 356findications for, 337–339, 338f–339f, 378–384, 379f–384fintegration of, 341–342interim, 355internal anchorage with, 352intramobile element with, 350, 351fintramucosal, 340, 340fjoining of, 355junctional epithelium for, 341, 350loading of, 376in mandible, 381fmasticatory forces transfer to bone, 376mini-, 355–357, 356fneedle, 348, 348fone-piece, 350f, 352one-stage placement of, 335open, 335, 336fosseointegration of, 341, 341f, 344, 360foverdentures retained by, 378placement/implantation ofclinical phase, 372–374, 372f–374f, 386fcomputer-navigated, 367–368, 368fdelayed, 337, 355description of, 335drill templates used in, 368f, 368–369examination before, 366exposure, 371, 371fimmediate, 337, 355, 356fimpression-taking for, 372–374, 372f–374finsertion, 369, 370f–371flaboratory phase, 374–376, 375f, 386fmucosal thickness over area for, 366, 367fone-stage, 335steps involved in, 369, 370fsummary of, 386fsurgical phase, 369–371, 370f–371ftwo-stage, 337platform switching, 375fretentive elements on, 377fscrew fixation of, 353screw-type, 347, 348fsetup for, 365, 366fseverely reduced residual dentition restored with, 383, 383fshort, 352, 353fsingle-tooth, 337, 376, 378–379, 379fsplinting of, 385subperiosteal, 340, 340fsuperstructurescementation connection for, 354f, 354–355description of, 350design guidelines for, 384–385fabrication of, 374–376, 375fframeworks for, 385screw fixation connection for, 353–354, 354fsurface ofplasma coating of, 346, 346froughness of, 344–345, 345ftemporary, 337, 353, 355titanium, 344–347, 345f–346ftransdental, 339, 339ftransosseous, 339, 339ftreatment planning for, 365–366, 365f–366ftwo-piece, 350f, 351two-stage placement of, 337zirconia ceramic, 346, 354Implant apex, 349f, 350Implant bars, 376Implant bed, 337, 349f, 370fImplant head, 350Implant materialsalloplastic, 342–343, 343fbiocompatibility of, 342bioreactive, 344mechanical properties of, 342metals, 342–343quality of, 342–343tissue reaction and, 343–344titanium, 344–347, 345f–346fImplant neck, 350Implant shoulder, 349f, 350, 375fImplantologycomputer-navigated, 367–368, 368fdefinition of, 335Impressionschewing, 249closed-mouth, 249closed-tray, 372f, 372–373crowns, 33f–37f, 33–36custom-tray, 248double-mix technique, 34, 35dual-phase technique, 33–34for implants, 372–374, 372f–374fin Ludwig technique, 318, 318f–319fmaterials for, 248–249mucostatic, 248of edentulous jaw, 247–249, 248fopen-tray, 373–374, 373f–374fring-supported, 34, 36f–37fsingle-phase technique, 33swallowing, 249In-Ceram, 56Incisive papilla, 262Industrially fabricated attachment fittings, 148, 149fInferior vestibular fornix, 264Infrabulge, 182, 182fInlay, occlusal, 13–14, 14fInlay restorationscomposite, 12composition of, 12, 13fdesign of, 12electroformed, 12fabrication of, 12indications for, 12metal, 12, 13f–14f 394IndexIonlays, 14, 14foverlays, 14, 14ftypes of, 12, 13fveneers, 15, 15fInlay splints, 14Insertion dentures, 86–87, 110–111Interalveolar angle, 294–295Interalveolar line, 245, 246f, 255f, 294Intercuspation, 317fInterdental gaps, fixed partial denture for, 240Interdental insertion partial dentures, 87, 111Interdental papilla, 19, 19f–20f, 375Interim implants, 355Interim prosthesis, 6Interocclusal registration, 249–251, 250f–251f, 325fIntramucosal implants, 340, 340fInverted cone, 134fIPS Empress system, 56–57, 57fJJacket crownsacrylic resin, 51, 53, 53f–54f, 79description of, 51–54, 52f–53fthimble crowns and, 89Jackson clasp, 184fJ-clasps, 184f, 185Jüde’s working method, 304–305, 305fJunctional epithelium, 341, 350KKennedy topographic classification, 106, 107f, 383Keying, 300Kinetics, 218, 219Kretschmer constitutional typology, 272fLLaminates. See Veneer(s).Latches, 158Lateral movements, 2Laterofrontal interdental insertion partial denture, 87Laterofrontolateral interdental insertion partial denture, 87Law of clasp lines, 223Leucite crystals, 63, 63fLeverdefinition of, 217dentures affected by, 227f–230fillustration of, 216fresistance lever arms, 226–227, 228fLight point indicator, 35Lingual bar, 118Lingual plates, 118, 118fLingual pull-off forces, on partial crowns, 73, 74fLocator, 377fLocks, 158, 159fLudwig technique, 318–321, 318f–321fMMalocclusions, 2Mandibledenture frameworks in, 118–119, 119fedentulousmodel analysis of, 264–266, 265f–266f, 327foverdenture restoration of, 384, 384fMandibular canines, in complete denture, 274–275Mandibular central incisors, in complete denture, 274, 274fMandibular incisal point, 293Mandibular molars, in complete denture, 279f, 279–280Mandibular premolars, in complete denture, 280, 280f, 332fManually fabricated attachment fittings, 136f–137f, 136–138Marginal periodontiumdefinition of, 37foreign body irritation of, 37–39inflammatory reactions at, 339Maryland bridges, 90Masticatory forceson partial crowns, 74f, 75, 77fon periodontal tissues, 5, 5fMasticatory muscles, 4Masticatory stability, 310–312, 311f–312fMasticatory systemcomplete edentulism effects on, 4, 4fcoronal restoration effects on, 22description of, 1impairments in, digestive processes affected by, 5physiology of, 314fMatrix, 166Maxilladenture frameworks in, 120, 121fedentulousalveolar process in, 247model analysis of, 262–263, 262f–263f, 326fMaxillary canines, in complete denture, 277, 277fMaxillary central incisors, in complete denture, 275–277, 276fMaxillary lateral incisors, in complete denture, 276f, 277Maxillary molars, in complete denture, 281, 284Maxillary premolars, in complete denture, 281, 332fMaxillary sinus elevation, 358–360, 359f–362fMaxillary tuberosity, 247Mechanical systems, 214–217Mesial tipping, 198, 199fMesiobuccal cusp, 45f–46fMesiolingual cusp, 45f–46fMetal framework, 66Metal inlay restorations, 12, 13f–14fMetal oxides, colored, 63, 64fMetal-ceramic, 63Metal-ceramic crowns, 65Microanalyzer, 200fMilling base, 173fMini-implants, 355–357, 356fMinimally invasive restorations, 90Mock-up, 365, 366fModel cast dentures, 116, 121fModulus of elasticity, 194Molars, in complete denturemandibular, 279f, 279–280maxillary, 281, 284Mortar-and-pestle teeth, 259, 308Movable bearing, 215Mucosa-borne dentures, 221Mucosa-borne prosthesis, 110 395IndexPMultispan partial denture, 95, 95f, 99Multispan terminal fixed partial denture, 87, 88fMylohyoid muscle, 305fMyopathies, 3NNeedle implants, 348, 348fNeutral equilibrium, 215Neutral tooth position, 254Newton’s laws of motion, 214Ney clasps, 203, 204f–207fNey No. 1 clasp, 203, 204fNey surveying system, 198OOcclusal crown, 79Occlusal disorders, 2Occlusal inlays, 13–14, 14fOcclusal plane, teeth position relative to, 256–258, 256f–258fOcclusal pull-off forces, on partial crowns, 73Occlusal rests, for cast clasps, 189–191, 190f–191f, 203, 208, 223Occlusal surfacefunctional, 70fof full crowns, 42f–47f, 43preparation of, for crowns, 32, 32fOcclusion rim, 250Onlays, 14, 14fOpen attachments, 152, 152f, 154–155Open implants, 335, 336fOpen ring telescope, 140fOpen-tray impressions, 373–374, 373f–374fOral hygiene, 23Orthophosphoric acid, 15Osseointegration, 341, 341f, 344, 360fOsteoporosis, 243, 244fOverdenturesanchoring and supporting elements with, 377f, 377–378, 385description of, 155, 155f, 376–378, 377fedentulous mandible restoration with, 384, 384fOverjet, 270, 270f, 282f–283f, 316Overlays, 14, 14fOversize, 131PPalatal straps, 120, 121fParalingual pockets, 289, 290fParallel fittingsabrasion of, 135accuracy of, 131, 132fclearance fit, 131–133clearance size for, 133–134definition of, 131displacement of matched parts, 135error analysis of, 133–135manually fabricated attachment fittings, 136f–137f, 136–138parallelism of, 134–135, 135fpress fit, 131–132production of, 131–132quality of fit, 133, 133ftransition fit, 131–132Parallelometer, 198, 200fPartial crownsadvantages of, 71as partial denture abutments, 89bending open of, 74, 74fchannel-and-pin preparation for, 72fchannel-shoulder-pin retention of, 73–75, 74f–75fclassification of, 71–73, 72fcontraindications for, 71description of, 18f, 22, 22flingual pull-off forces on, 73, 74fmasticatory forces on, 74f, 75, 77focclusal pull-off forces on, 73parapulpal pin retention of, 74, 74fpull-off forces on, 73, 74fretention of, 73–75, 74f–75ftypes of, 71, 72fPartial denturesabutment tooth for, 81abutments for, 88–90acrylic resin veneer crowns as abutments for, 88, 96anterior, 376body ofanchor and, connection between, 94–96design of, 92–94path of, 101–103saddle, 92, 112–116bonded, 90–92, 91fcantilever, 88, 88fceramic veneers as abutments for, 88–89characteristics of, 86–88, 87fclassification of, 110–112, 111fclosed occlusal field of, 85components of, 82f–83fcontraindications, 84definition of, 81design planning of, 230–232division of, 94, 95ffixed. See Fixed partial dentures.frameworks for, 116–117, 117f, 376full crowns as abutments for, 88function of, 85–86hygienic, 93findications for, 83interdental insertion, 87loading of, 101fmucosa-borne, 110multispan, 95, 95f, 99partial crowns as abutments for, 89periodontal support of, 223fperiodontally supported, 110physiologic conditions, 231–232polishing of, 180fpontics and, 81, 84, 93fpost crowns as abutments for, 89posterior, 376precision attachments for, 94primary splinting with, 85removable. See Removable partial dentures.resin-bonded, 90rigid structure of, 85, 94, 95fsaddle, 92, 93fslit, 93f, 94space, 94span of, 99fstatic relationships for, 231statics of, 98–100, 98f–100f, 211–240tangential, 92, 93ftapered crowns with, 147fterminal, 87–88thimble crowns as abutments for, 89, 89fthree-unit partial denture and inner telescope, 170, 171f–180ftissue loading-based classification of, 110types of, 86–87, 87fPartial prosthesis, 6 396IndexPPartially edentulous archesabutment teeth used in restoration of, 146, 147fclassification of, 105, 106f–109fPartially edentulous dentitionmalocclusions in, 2progressive destruction of, 4reflex arc in, 5Passive retention accessories, 158, 159fPath of insertion, 198Patrix, 166Peri-implantitis, 339Periodontal pocket, 1Periodontal tissues, masticatory forces on, 5, 5fPeriodontally supported prosthesis, 110Periodontitis, 339Physics, 211Physiodens teeth, 316, 316f–317fPhysiognomy, 316fPlatform switching, 375fPonticson abutment teeth, 84, 85f, 101, 102fcantilever, 101, 101f–102fceramic-veneered, 92definition of, 81hygienic, 94loading of, 103fPorcelain crown, 55, 56fPost and core crowns, 75, 76f, 78, 78fPost crownsas partial denture abutments, 89compressive forces on, 76conical post for, 76, 77fcustom-made post, 78–79, 79fcylindric post for, 77, 77fdescription of, 18f, 22, 22fdesign of, 78–79indications for, 75post and core crown versus, 75–76retention of, 76–77, 77fsimple, 79threaded post for, 77, 77ftorsional stress on, 76, 77fPosterior palatal strap, 120, 121fPosterior partial dentures, 376Posterior teethalveolar ridge of, 246in complete dentures, 278–284, 279f–283fcrowns on, 69–70, 70fPostpalatal sounds, 261, 261fPotash feldspar, 63Pound line, 302Precision fittings, 129–131, 130fPrefabricated crowns, 48Premolars, in complete denturemandibular, 280, 280f, 332fmaxillary, 281, 332fPreparation marginchamfer preparation, 30, 30f, 33chamfer/shoulder, 30f, 31, 66, 68fdefinition of, 25, 26fforms of, 27f–30f, 27–31for full-cast crowns, 40gingival, 26fshoulder preparation, 28–30, 29f–30f, 33, 38fsubgingival, 26fsupragingival, 25–26, 26ftangential preparation, 27–28, 33, 38fPress fit, 131–132Primary splinting, 85, 383, 385Prophylactic function, of dental prostheses, 6, 7fProstheses, dental. See also Biologic prosthetics.anchoring of, to residual teeth, 5definition of, 6functions of, 6, 7fgoals of, 6immediate, 6importance of, 5interim, 6mixed support for, 110partial, 6resin-bonded, 90, 91fProsthetic equator, 182, 182f, 199f–200fProtective crowns, 21, 21fProtrusive movements, 2Pull-off forces, on partial crowns, 73, 74fRReflex arc, 5Regulating function, of dental prostheses, 6, 7fRemovable partial dentures. See also Partial dentures.advantages of, 87, 97fanchoring and supporting elements forabutment teeth connection with, 125cast clasps, 125clasp anchors, 125connectors to, 119description of, 96, 112, 122function of, 124f, 124–125mechanical fittings, 112, 114, 122prefabricated matched components, 122splinting, 125, 125fspring fit, 122telescopic anchors, 122types of, 122, 123farticulated coupling of, with residual dentition using, 126, 128fbase of, 112, 113fdecoupling of, 126, 128definition of, 6disadvantages of, 96fixed partial dentures versus, 86f, 87frameworks foracrylic resin, 116connectors of, 117fdescription of, 112design principles of, 116–117, 117fin mandible, 118–119, 119fin maxilla, 120, 121ftongue clearance in, 117fully, 96horizontal forces on, 124, 125fmixed-support, 385movements of, 124relinability of, 114residual dentition coupling with, 126–128, 127frigid coupling of, with residual dentition using, 126, 127f 397IndexSsaddle of, 112–116, 113f, 115fsecondary splinting with, 85semirigid coupling of, with residual dentition using, 126, 127fseverely reduced residual dentition restored using, 383, 383fstructural features of, 112–114, 113fthrust moments on, 124Replacement crowns, 21, 129Repulsion forces, 214Residual dentitioncase studies of, 232–240design descriptions for, 232–240forces on, 217–218removable partial denture coupling with, 126–128, 127fseverely reduced, restoration of, 383, 383fResilient attachments, 155Resilient bars, 156–157Resin-bonded partial dentures, 90Resin-bonded prostheses, 90, 91fResistance lever arms, 226–227, 228f, 233Resorptive atrophy, 243Restorationsamalgam, 10, 10fbone-supported tooth, 110classification of, 8composite, 10–11, 11fglass-ionomer cement, 11gold compaction, 11, 11fimplant-borne, 355, 376inlay. See Inlay restorations.loading of, 98purpose of, 8tooth preparation for, 8, 9fRestorative materialsamalgam, 10, 10fcomposites, 10–11, 11fdescription of, 10–11foreign body irritation of marginal periodontium caused by, 37glass-ionomer cement, 11Restorative treatment, 8Resultant, 212, 212fRetromolar triangle, 289, 302, 316Rigid coupling, of removable partial dentures with residual dentition, 126, 127fRing-supported impression, 34, 36f–37fRobolock lock, 159fRoller attachments, 160–161Root crown anchors, 162, 163fRothermann anchorage system, 162SSaddle, denturealginate impression of, 114closed-saddle, 115, 115fdescription of, 92, 93fdesign principles for, 114–116, 115fextended, 114free-end. See Free-end saddles.functions of, 112, 113fof removable partial dentures, 112–116, 113f, 115fSagittal and lateral symphysis path, 293Scalar quantities, 211Schreinemakers’s working method, 302, 303fScrew-type implants, 347, 348fSecondary splinting, 85, 383, 385Self-tapping threads, 347, 348fSemi-ellipsoid wax profile, 201Semirigid coupling, of removable partial dentures with residual dentition, 126, 127fSetupdefinition of, 365for implants, 365, 366fSeven-eighths crown, 18f, 71, 72fSharpey fibers, 5, 84Shear distribution arm, 137, 137fShear distributors, encircling catch with, 137f, 137–139Shoulder preparationfor ceramic-fused-to-metal crowns, 66crown margin mistakes with, 38f, 39description of, 28–30, 29f–30f, 33for jacket crowns, 52fSibilants, 260f, 261Silanization method, 61fSimplex articulator, 293, 294fSingle-arm clasps, 184f, 185Single-span terminal partial dentures, 87, 88fSingle-tooth implants, 337, 376f, 378–379, 379fSingle-tooth rehabilitation, 17Single-value bearings, 215Single-wing bonded partial dentures, 90Sinking, of mucosa-borne dentures, 221Sintering, 64f, 65Sinus elevation, 358–360, 359f–362fSinus floor augmentation, 363Skeleton plate, 120, 121f, 236Slide-type lock, 158, 159fSliding friction, 220, 220fSlit partial denture, 93f, 94Slope force, 196Smile line, 250Snowshoe principle, 154Soldering, 169Space partial dentures, 94Spacer technique, 169Splinting, 85, 86f, 125, 187, 189, 383, 385Split clasp, 204, 205fSpring bolt anchor, 141fSpring characteristics, 219Spring constant, 196, 219Spring deflection, 182, 192, 194, 199, 201–202, 219Spring fit, 122Spring force, 194–196, 195f, 219–220, 220fSpring-bolt anchor, 158Sprueing, 47f, 48Stable equilibrium, 215Stable tooth position, 254Static friction, 220, 220fStatically determinate system, 215Statically indeterminate system, 215, 221, 222fStaticsdefinition of, 211forces on residual dentition, 217–218friction, 219–220mechanical systems, 214–217mixed support, 221, 222fNewton’s laws of motion, 214of complete dentures, 253f–258f, 253–258of partial dentures, 98–100, 98f–100f, 211–240spring force, 219–220 398IndexSStud anchors, 158Subgingival preparation margin, 26fSublingual bar, 118, 119f, 234Sublingual roll, 289, 290fSubperiosteal implants, 340, 340fSuction effect, 286–288, 289f–291fSupportive crowns, 21Suprabulge, 182, 182fSupracoronal transverse connector, 118Supragingival preparation margin, 25–26, 26fSurveying casts, 198–200, 199f–200fSwallowing impression, 249Swivel-type lock, 158, 159fSymphysis point, 293TTangential partial dentures, 92, 93fTangential preparationfor ceramic veneers, 68fcrown margin mistakes during, 38f, 39description of, 27–28, 33for jacket crowns, 51Taper angle, 142–144, 144f, 147Tapered crown, 145, 145fT-attachments, 148, 149f, 160, 160f, 232–233, 237T-clasps, 184fTeeth. See also Anterior teeth; Dentition; Posterior teeth; specific teeth.abutment. See Abutment teeth.devitalized, 75, 75felongation of, 2, 2ftipping of, 1, 3f, 5, 198, 199fTelescopic anchoring and supporting elementsactive retention accessories, 158, 159fbars, 156f–157f, 156–157components of, 164t–165tdefinition of, 122encircling catch with shear distributors, 137f, 137–139industrially fabricated attachment fittings, 148, 149fopen attachments, 152, 152f, 154–155parallel fittings. See Parallel fittings.passive retention accessories, 158, 159fprecision fittings, 129–131, 130fprefabricated attachmentsclassification of, 152fclosed attachments, 152, 152f, 154defined retentive force of, 150, 151fdegrees of freedom of, 152, 152fDegussa multi-CON system, 160f, 160–161, 164t–165tdovetail attachments, 160, 161fhinged attachments, 152, 152fintegration of, 169–170open attachments, 152, 152fperiodontal hygiene of, 150positional stability with, 152f–153f, 152–154practical value of, 150, 151fprocessing of, 166, 167f–168froot crown anchors, 162, 163fsoldering of, 169types of, 148, 149fresilient attachments, 155rigid coupling of denture with residual dentition using, 126, 127fthree-unit partial denture and inner telescope, 170, 171f–180ftypes of, 122Telescopic crownscharacteristics of, 164t–165tcomposition of, 139conical crowns. See Conical crowns.definition of, 139denture anchorage using, 378double-walled, 140, 141findications for, 140–141open ring telescope, 140frequirements of, 141Temporary implants, 337, 353, 355Temporomandibular diseases, 3Terminal occlusion, 53, 53fTerminal partial dentures, 87–88T-form, of manually fabricated attachment, 136, 136f, 138Therapeutic function, of dental prostheses, 6, 7fThimble crowns, 89, 89fThreaded post, 77, 77fThree-arm clasp, 184fThree-point contact, 266Three-quarter crown, 18f, 71, 72fThree-unit partial denture and inner telescope, 170, 171f–180fTipping, of teeth, 1, 3f, 5, 198, 199fTipping line, 235f, 238Titanium implants, 344–347, 345f–346fTooth lossanatomical changes after, 243–245caries as cause of, 23functional disorders after. See Functional disorders.Tooth migrationin edentulous space, 1, 2fposterior teeth, 3fTooth preparationfor crowns. See Crown(s), tooth preparation for.for restorations, 8, 9fTooth-prosthesis interface, 114–116Torque, 99–101, 100f, 213, 213fTraction lines, 227Transdental implants, 339, 339fTransition fit, 131–132Transosseous implants, 339, 339fTranspalatal strap, 120Transverse strap, 120Tripodization, 315fTrubyte articulator, 293Turning moment, 213Turn-type lock, 158, 159fUUhlig’s working method, 304Undercut gauges, 198, 200fUndercuts, 209fUnilateral interdental insertion partial denture, 86, 110Unstable equilibrium, 215, 217Unstable tooth position, 254VVector quantities, 211Veneer(s)ceramic, 63f–65f, 63–66description of, 15, 15ffull, 66preparation margin for, 30, 30f 399IndexZVeneer crownsacrylic resin, 60–61, 60f–62f, 88composition of, 59fdefinition of, 58description of, 39framework of, 59–60, 59f–60f, 62findications for, 58–59metal framework for, 61preparation for, 60silanization method for, 61fVertical dimension of occlusion, 249, 315Vertical masticatory forces, 218Vertical overbite, 69Vestibular fornix, 249, 275, 287, 287fVestibular placement, 266Vestibular veneer, 70fVolume, 214W“Watch-glass notch,” 60f, 62fWax-up techniquefor acrylic resin jacket crowns, 53for complete denture body, 333fdefinition of, 365for full-cast crowns, 40–41, 41f–42ffor partial denture, 175ffor telescope, 174fWild’s classification, of partially edentulous arches, 105, 106fWithdrawal force, 196, 197fWrought-wire clasps, 183–185, 184fXXenogeneic bone grafts, 363YYoung’s modulus, 194ZZirconia ceramic implants, 346, 354ZL DuoLock attachment, 164t–165t HohmannHielscherPrinciples of DESIGN and FABRICATION in ProsthodonticsContents1 Preprosthetics2 Coronal Restoration3 Features of Partial Dentures4 Removable Partial Dentures5 Telescopic Anchoring and Supporting Elements6 Resilient Anchoring and Supporting Elements7 Statics of Partial Dentures8 Complete Dentures9 Implant Terminology Principles of DESIGN and FABRICATIONin ProsthodonticsArnold HohmannWerner Hielscher

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