Posterior Teeth










Ch
apte
r 7
Poster
i
or
Teeth
Jordi
Manauta
Anna
Salat
Interview
with
Francesco
Mangani

/
" ."'\
; I
. (
. . .

''
Give
me
a lever
long
enou -
and
a place
to
stand
and
I
will
move
the
world.
''
Archimedes

280
I I
Prof Francesco Mangani holds degrees in medicine and general
surgery and a postgraduate certificate in odontostomatology.
At the University of Rome Tor Vergata,
he
holds the titles of
Associate Professor, Faculty of Medicine and
Surgery; Chair of
Restorative Esthetic Dentistry,
School of Dentistry; and Chair of
Dental Aesthetics, School of Dental Hygienists.
In
addition, Prof
Mangani serves
as
Head, Section of Restorative Esthetic Dentistry,
Tor Vergata University
Clinical Hospital.
He
is
an
active
member
of the Italian Academy of Conservative
Dentistry, the Italian Society of Endodontics, and the Italian
Society
of Conservative Dentistry,
as
well
as
an active
member
and cofounder of the Italian Academy of Esthetic Dentistry. His
research and
clinical activity are focused on restorative dentistry,
esthetics, and endodontics.
Prof Mangani
is
the author or coauthor of more than
260
scientific
publications about conservative
dentistry
and endodontics,
including the textbooks Manuale di Disegno e Modellazione Denta/e
(Textbook
of
Dental Design
and
Morphology, Martina,
1999)
and
Guidelines for Adhesive Dentistry:
The
Key to Success (Quintessence,
2009)
and the
multimedia
book Conservativa Estetica dei Settori
Latero-Posteriori: Restauri Adesivi
lndiretti
in Composito
nei
Denti
Trattati Endodonticamente
(Conservative Esthetic Restorations for
Endodontical/y Treated
Posterior Teeth,
UTET,
2008).
He
lectures
extensively
at congresses all over the world.

Q:
Why
is
stratification important
in
posterior teeth?
Is
it done only to improve esthetics?
It
is
well known among clinicians that,
even
if there are
no
unequivocal data, all methods for placing composite
resin
in
a cavity aim to increase the free surface of the
material and to decrease the configuration factor
(C
factor). This is independent of the horizontal, vertical,
or oblique (which
is
my favorite) layering technique
applied.
The
choice to layer is mandatory, both when
the
final cavity design
is
deeper than 2
mm
(as often
occurs
in
the lateroposterior sectors of the mouth)
and when the
clinician, following a minimally invasive
approach, prepares
small cavities that are complex and
difficult to restore because of awkward location.
To
reduce the intrinsic limitations of the composite itself,
the use of adequate polymerization to guarantee the
highest degree
of
conversion
is
of primary importance.
It
is
now known that the physical and mechanical
features of a composite resin can
be
negatively affected
by
insuffipient passage of the curing light through the
material,
even
for thicknesses slightly greater than 2
mm. Moreover, the uncured monomer
results
in
biologic
problems
of tissue leakage and acts
as
a plasticizer,
increasing the hygroscopicity of the
material: This
results in
an
early loss of the esthetic properties of
the
material, which is subject to more variations and
chromatic changes.
The
excellent optical features of the new composite
resin
materials, together with the use of correct layering
techniques,
allow
us
to provide
an
esthetic appearance
to something that must
be,
first of all, functionally
correct.
Becau$e I've
been
practicing dentistry for 30
years, I can affirm that the pleasure of and the search
for esthetics cannot take precedence over what
we
have
to consider
as
the primary aim and the target of all
our restorative interventions:
The
restoration of correct
function.
Thus,
in
brief, layering
is
necessary: first, to compensate
for the intrinsic
limits resulting from the chemistry of
composite
materials, and second, but
no
less
importantly,
because there is not and there never will
be
function
without
morphology, regardless of the esthetics. Citing
my teachers,
I want to emphasize that nobody should
ever forget that last point. Reproduction of the correct
anatomy
via
layering
is
the target to achieve every time
we
restore a carious or traumatized tooth.
261

252
Introduction
A correct understanding of tooth structures and
spatial visualization of enamel and dentin allow
us
to perform accurate reconstruction of the
dentition.
Function and esthetics are synonymous, and the
proof of this assertion
is
the posterior teeth.

nal Technique) Pizza Technique
The
secret to fabricating esthetic and functional posterior teeth
is
to generate correct and precise
occlusal anatomy. It has been well proven that single-shade stratification techniques solve the
majority of cases
correctly.
To
achieve a correct anatomy through layering,
we
propose a sectional
modeling
technique in which one increment
is
used for each cusp.
Each
one of these increments,
when
correctly modeled, resemble pizza slices.
The
procedure
is
started with the simplest cusp,
and then one cusp
is
added at a
time
to acquire more anatomical references to define the remaining
and more
difficult
structures. The choice of the
first
cusp and the order of layering are personal,
but
we
suggest
starting
with the easiest (most regular-shaped and medium-sized) cusp and working
toward the most
difficult
(irregularly shaped and large- or very smallsized) cusp.
A sectioned
stratification
on
a max-
illary
left
molar
will be performed
in white composite as
an
example.
The procedure will be started
on
an
occlusal Class I cavity with very
few
anatomical references.
Once the
first
cusp is cured, the
next is
modeled. It is not necessary
to
worry
about
deformation
of the
previous cusp. Before
polymeriza-
tion, the buccal sulcus
must
be
defined.
2
54
The
mesiobuccal cusp
is
initiated
with a
small increment of compos-
ite resin. This
is
the easiest cusp
on
this molar because of its regu-
lar
shape. Before polymerization,
slopes will
be
developed, and the
limits, which
must
be
located at the
main
sulcus where the rest of the
cusps
will converge, will
be
defined.
When
all the buccal anatomical
references are finished, the palatal
cusps are developed, in
this
case
the transverse ridge.

Once
the
tran
sve
rse rid
ge
is
po-
lymerized
, the
distolingual
cusp is
modeled, and the
distal
sulcus will
be defined at the
sa
me
time
.
The
larger cusp (mesiolingual), which
at the beginning was the
most
diffi-
cult
to model, now will
be
easy to de-
velop
from
all the previou sly created
anatomical references.
The
final appearance should
be
a mo-
lar with rich anatomy,
multiple
eleva-
tions and depressions, and a harmo- .
nious, regular surface.
Modeling of an occlusal
sur-
face requires three specific
instruments:
(8a) A rounded
microplug-
ger to develop slopes.
(8b)
A sable brush soaked
in
modeling
liquid
to smooth
the slopes and remove
roughness.
(8c) A very subtle spatula,
the
tip
of the Fissura instru-
ment
(LM -Arte,
LM
Instru-
ments),
or
a
No.
11
scalpel
blade to create a groove.
285

266
Complete Crown Construction
Complete anatomical stratification
is
critical to
reproduce medium and
large restorations.
Knowledge of the means to achieve complete anatomical
reproduction of the entire crown not only allows
us
to
create more
complex color effects, it also opens the door
to advanced posterior
morphology and biomechanics.
It
is
crucial to carry out the stratification
in
segments.
This creates a variety of densities
in
the interior,
resulting
in
a mechanically efficient and contraction-
free restoration.
Several authors support composite resin
as
the first-
choice material for total cusp coverage, because of its
excellent clinical performance, especially
that
of hybrid
composites.

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Chapter 7 Posterior Teeth Jordi Manauta • Anna Salat Interview with Francesco Mangani / " ."'\ ; I . ( . . . '' Give me a lever long enou -and a place to stand and I will move the world. '' Archimedes 280 I I Prof Francesco Mangani holds degrees in medicine and general surgery and a postgraduate certificate in odontostomatology. At the University of Rome Tor Vergata, he holds the titles of Associate Professor, Faculty of Medicine and Surgery; Chair of Restorative Esthetic Dentistry, School of Dentistry; and Chair of Dental Aesthetics, School of Dental Hygienists. In addition, Prof Mangani serves as Head, Section of Restorative Esthetic Dentistry, Tor Vergata University Clinical Hospital. He is an active member of the Italian Academy of Conservative Dentistry, the Italian Society of Endodontics, and the Italian Society of Conservative Dentistry, as well as an active member and cofounder of the Italian Academy of Esthetic Dentistry. His research and clinical activity are focused on restorative dentistry, esthetics, and endodontics. Prof Mangani is the author or coauthor of more than 260 scientific publications about conservative dentistry and endodontics, including the textbooks Manuale di Disegno e Modellazione Denta/e (Textbook of Dental Design and Morphology, Martina, 1999) and Guidelines for Adhesive Dentistry: The Key to Success (Quintessence, 2009) and the multimedia book Conservativa Estetica dei Settori Latero-Posteriori: Restauri Adesivi lndiretti in Composito nei Denti Trattati Endodonticamente (Conservative Esthetic Restorations for Endodontical/y Treated Posterior Teeth, UTET, 2008). He lectures extensively at congresses all over the world. Q: Why is stratification important in posterior teeth? Is it done only to improve esthetics? It is well known among clinicians that, even if there are no unequivocal data, all methods for placing composite resin in a cavity aim to increase the free surface of the material and to decrease the configuration factor (C factor). This is independent of the horizontal, vertical, or oblique (which is my favorite) layering technique applied. The choice to layer is mandatory, both when the final cavity design is deeper than 2 mm (as often occurs in the lateroposterior sectors of the mouth) and when the clinician, following a minimally invasive approach, prepares small cavities that are complex and difficult to restore because of awkward location. To reduce the intrinsic limitations of the composite itself, the use of adequate polymerization to guarantee the highest degree of conversion is of primary importance. It is now known that the physical and mechanical features of a composite resin can be negatively affected by insuffipient passage of the curing light through the material, even for thicknesses slightly greater than 2 mm. Moreover, the uncured monomer results in biologic problems of tissue leakage and acts as a plasticizer, increasing the hygroscopicity of the material: This results in an early loss of the esthetic properties of the material, which is subject to more variations and chromatic changes. The excellent optical features of the new composite resin materials, together with the use of correct layering techniques, allow us to provide an esthetic appearance to something that must be, first of all, functionally correct. Becau$e I've been practicing dentistry for 30 years, I can affirm that the pleasure of and the search for esthetics cannot take precedence over what we have to consider as the primary aim and the target of all our restorative interventions: The restoration of correct function. Thus, in brief, layering is necessary: first, to compensate for the intrinsic limits resulting from the chemistry of composite materials, and second, but no less importantly, because there is not and there never will be function without morphology, regardless of the esthetics. Citing my teachers, I want to emphasize that nobody should ever forget that last point. Reproduction of the correct anatomy via layering is the target to achieve every time we restore a carious or traumatized tooth. 261 252 Introduction A correct understanding of tooth structures and spatial visualization of enamel and dentin allow us to perform accurate reconstruction of the dentition. Function and esthetics are synonymous, and the proof of this assertion is the posterior teeth. nal Technique) Pizza Technique The secret to fabricating esthetic and functional posterior teeth is to generate correct and precise occlusal anatomy. It has been well proven that single-shade stratification techniques solve the majority of cases correctly. To achieve a correct anatomy through layering, we propose a sectional modeling technique in which one increment is used for each cusp. Each one of these increments, when correctly modeled, resemble pizza slices. The procedure is started with the simplest cusp, and then one cusp is added at a time to acquire more anatomical references to define the remaining and more difficult structures. The choice of the first cusp and the order of layering are personal, but we suggest starting with the easiest (most regular-shaped and medium-sized) cusp and working toward the most difficult (irregularly shaped and large- or very smallsized) cusp. A sectioned stratification on a max-illary left molar will be performed in white composite as an example. The procedure will be started on an occlusal Class I cavity with very few anatomical references. Once the first cusp is cured, the next is modeled. It is not necessary to worry about deformation of the previous cusp. Before polymeriza-tion, the buccal sulcus must be defined. 254 The mesiobuccal cusp is initiated with a small increment of compos-ite resin. This is the easiest cusp on this molar because of its regu-lar shape. Before polymerization, slopes will be developed, and the limits, which must be located at the main sulcus where the rest of the cusps will converge, will be defined. When all the buccal anatomical references are finished, the palatal cusps are developed, in this case the transverse ridge. Once the transverse ridge is po-lymerized, the distolingual cusp is modeled, and the distal sulcus will be defined at the same time. The larger cusp (mesiolingual), which at the beginning was the most diffi-cult to model, now will be easy to de-velop from all the previou sly created anatomical references. The final appearance should be a mo-lar with rich anatomy, multiple eleva-tions and depressions, and a harmo- . nious, regular surface. Modeling of an occlusal sur-face requires three specific instruments: (8a) A rounded microplug-ger to develop slopes. (8b) A sable brush soaked in modeling liquid to smooth the slopes and remove roughness. (8c) A very subtle spatula, the tip of the Fissura instru-ment (LM -Arte, LM Instru-ments), or a No. 11 scalpel blade to create a groove. 285 266 Complete Crown Construction Complete anatomical stratification is critical to reproduce medium and large restorations. Knowledge of the means to achieve complete anatomical reproduction of the entire crown not only allows us to create more complex color effects, it also opens the door to advanced posterior morphology and biomechanics. It is crucial to carry out the stratification in segments. This creates a variety of densities in the interior, resulting in a mechanically efficient and contraction-free restoration. Several authors support composite resin as the first-choice material for total cusp coverage, because of its excellent clinical performance, especially that of hybrid composites. Mesia I Buccal Palatal / The mesial, buc-cal, and palatal aspects of a plas-tic die that will act as a base for this exercise are shown. A high-chroma-ticity dentin (A6) is placed in the neck, fading in the middle third. A long cone is sculpted for each cusp, with the same high-chro-maticity dentin (A6). This simu-lates the normal anatomy. The chosen base color dentin (A3) is used to create the buccal and lin-gual walls, prop-erly divided by the buccal sulcus and palatal sulcus, re-spectively. Walls are connect-ed with the same dentin (A3) while the marginal ridge is modeled. 257 266 The previous steps leave "a circumferential structure and empty occlusal surface. A small increment of the base color dentin compos-ite (A3) will be placed in the ridge of each cusp, which should not be polymerized yet. The first layer of the occlu -sal surface is made with a high-Chroma dentin com-posite (A6), which is not po-lymerized yet. The mass is modeled in place with a rounded plug-ger and polymerized. The spatula is used to draw a sketch of the occlusal anatomy. Now the material is polymerized. The opalescent material is placed. on the axial walls of each cusp and blended from the top of the cusp to about 2 mm in an apical direction. The presence of the opalescence should be unnoticeable. Finally, the enamel layer on the outer walls is modeled, once again turning the occlusal sur· face into a void space where we can freely stratify. 269 The previous steps created a circumferential structure ("fish mouth") that leaves space for the occlusal surface. Transverse ridge buildup is com-pleted with the same enamel mass. A brown-orange sulcus (see page 295) has been developed with brown in the center and orange in the periphery. 290 The layering of the occlusal enam-el composite is started. The sec-tional (pizza) technique is used, starting with the mesiobuccal cusp, which is the easiest. Distopalatal cusp buildup and dis-tal groove modeling are complet-ed. Distobuccal cusp buildup is ac-complished without invading its natural limit (buccal groove). Mesiopalatal cusp buildup, main sulcus modeling, and occlusal stratification are completed. The restoration is shown after the final enamel composite modeling and before the finishing and polishing stage. Although some gloss is apparent, this effect is the result of the uncured composite in the oxygen -inhibited layer. After high -gloss polishing the final appearance should show a regular surface and natural shine. Note the chromatic aspect of the external walls. The cervical area has a powerful color that vanishes toward the tip of the cusps, which are translucent. The. polished occlusal surface gains naturalness and should not lose anatomy or texture at the fin -ishing stage. With only four colors, it has been possible to achieve a highly characterized posterior tooth. 291 After dentin is modeled and before the enamel layering begins, small increments of white intensive (+) are placed in a "roll "shape (see 12a, 12b). Enamel composite is placed on the external walls to create a fish mouth and enable building of the occlusal surface with the sectional technique. Occlusal ridges For highly characterized occlusal surfaces, we suggest the use of white effects, especially in areas where enamel is thicker . • • 292 Cusps must be characterized one at a time. Each cusp can hold many rolls, depending on its size, but normally there are one to four. With the same enamel composite, each cusp is covered one by one, starting from the easiest, in this case the mesiobuccal cusp. The occlusal surface gains natural -ness when many of these microin-crements are placed. After polymerization the next cusp is characterized, always generating the sulcus that will determine their division. With the proper order, all the buc-cal cusps are generated. Increments must be done in a white composite resin, placed in very small amounts with a fine spatula and a roll shape. As cusps are modeled , more refer-ences are gained , thus simplifying those that were the most complex at the beginning. A brown-ocher stain is developed, with brown in the center and ocher in the periphery. The completion of stratification should be easy after all cusps have been previously made. Finishing and polishing are com-pleted. 293 294 An occlusal stain is generally .... in-terpreted as the result of perspective and is a difficult tasl5 The classification we propose distinguishes 10 types of stain, which are generated from a two· color mixture, one in the center and one in the periphery. Occlusal Stain Classification .. Center Orange: A slight chromatic stain that blends with the dentin and looks almost transparent. A flow-able A3 composite is suitable as well. Ocher: An intermediate-intensity stain that is visible as a reddish (light brown) stain. Brown: A high-intensity brown stain that is the most common stain . Black: The highest-intensity stain, representing the most opaque mass, normally modified. 295 It is important to distinguish occlusal characterizations not only by color, but also by shape, location, and disposition if we are to simulate them correctly. (1) The vast majority of stains are found in the main occlusal sulcus, usually from the center · to periphery, but sometimes their continuity is interrupted, looking like a dashed line. Stains are rarely located in supplementary sulci or outside the central grooves. 296 (2) Incorrectly placed occlusal sta ins often result in a smear ef-fect and fading spots. II (3) Correctly placed occlusal stains create a sharp and clean sulcus. The color becomes stron-ger, and the effect lasts longer be-cause the layer of stain is thicker. The use of ceramic powders to reproduce or modify stain colors has interesting potential. In our experience, for example, it is difficult to find suitable black stains for occlusal characterizations. Generally the stains are pure black and have some degree of translucency, which gives them an unpleasant appearance once they are layered. For those reasons, the brown stain of our choice (4), which is opaque, dark, and chromatic, can be intensified with black ceramic powder (5) to obtain an ideal, almost·black (6) characterization like that found in natural teeth. 297 Non-edge Technique ................................................................................................................................................................................................................................................................................ 298 Described by Dr Dario Adolfi, this technique is indicated especially for ceramic crowns that have lost their anatomy before cementation. This situation can result from overtiring of ceramics, large occlusal adjustments, or deficient modeling. In these situations, the anatomy should be redefined. An old tungsten bur is modified with a diamond disk. Both instruments must be rotating during this procedure; trim-ming should continue until a fine tip is created. J l A recently baked ceramic res-toration demonstrates poor anatomy. A rounded No. 1/2 diamond bur is used to develop the slopes that characterize each ridge from each cusp, widen-ing from the bottom to the surface. Small add-on mass correc-tions are applied to enhance the anatomy, and stain is ap-plied before the glaze firing. A map of the main grooves is drawn with a pencil. The main sulci are redefined a second time with the modi-fied bur. The anatomy of the crown has been restored . Because of the hardness of tungsten , the bur is able to heat the ceramic surface and penetrate it, creating sharp grooves. The restoration is sandblast-ed at 2-bar pressure from a 10-cm distance to remove the debris from the milling. 299 Principles of the non-edge technique The non -edge technique for ceramic restorations: ·We are not milling, we are microfiring the ceramic. • The tungsten carbide bur rotating at 30,000140,000 rpm can reach 1,000°C because of the friction against the ce-ramic. • A micromeltdown and fusion of the ce-ramic occurs specifically where the tip of the bur is applied. • This "violent" procedure creates crys-talline disarray and microfractures and therefore the ceramic becomes fragile; subsequent glaze firing will rearrange the structure and melt the microfrac-tures, restoring the complex to a one-piece strong ceramic again. This technique can be applied to com-posite resins: • The composite must be completely po· lymerized. ·The composite should be milled with a superfine multiblade bur, because it is the only bur capable of milling com-posite with such a fine tip. Diamond burs, even the thinnest flame-shaped burs, usually have a very thick tip. • The speed of the handpiece should not surpass 10,000 rpm. ·Pressure should be feather-light. •The restoration should be sandblasted before stain application. • The technique is completed with me· chanical polishing to a high gloss. Ceramist: Luis Alberto Villanueva, Zaragoza , Spain. 301 306Ceramist: Ferran Puig, Mollerussa, Lerida, Spain. 307Ceramic layering is particularly difficult, because postfiring shrinkage must be taken into account. Natural posterior anatomy depends primarily on two factors, sharp relief and well-defined grooves.This is performed with appropriate space distribution, making the tooth anatomically correct and therefore more esthetic. If we have correctly defined the so-called fish mouth (perimeter limit of the occlusal surface), it is much easier to manage the occlusal area. In this way, modeling becomes more predictable. It is always advisable to start with the external portion of the cusps and close the perimeter cusp by cusp. As with composite, when ceramics are used the occlusal surface is developed using the sectional technique with just minor modifications regarding the handling.Morphology: For a natural posterior anatomy, it is necessary to work with an extremely fine-tipped brush (N.Era, Smile Line), which will allow us to reach any area in the occlusal surface. The mass must be provided with optimum texture, so the ceramic mass has to be malleable and have plasticity. In this way we can reproduce any desired detail by adding small increments of ceramic and packing it with the brush.Grooves: Correct definition of the sulci with the fine-tipped brush is essential before firing. There is a high risk of postfiring ceramic separation when the sulci are defined with sharp instruments such as endodontic files or blades.Surface texture: The smoothing of raw ceramics with an extra-smooth brush allows creation of a very precise surface. For a magnificent final effect, a mixture of 50% glazing powder and 50% ceramic will be placed on the ridges to highlight and enhance the anatomy of the internal portion of the cusps.Ceramic dehydration: When modeling takes too long, ceramic masses start to dry. There are two ways to recover moisture: The first is to have an atomizer with distilled water available, and the second is to create a capillary effect by connecting the crown to our liquid container with an absorbent strip of paper; the latter technique may take longer but the hydration is more effective.Working with Ceramics 308 Conclusions 1. Incremental application of the stratification layers is obligatory, especially when a freehand modeling technique is used in posterior teeth. 2. Material contraction and polymerization depth are still problems. New materials that promise the ability to apply thick layers are just more transparent and contain a greater amount of catalyst, which means that they are less esthetic and have inferior mechanical properties. 3. The sectional (pizza) technique allows a systematic approach to development of a three-dimensional shape, color, and contraction stress control in occlusal surfaces. 4. Stain application becomes an involuntary self-education to model a correct sulcus. 5. Modeling with burs and corrections with rotating instruments should be avoided as much as possible. 309

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