Treatment of Endodontic Disease










8
Treatment
of Endodontic
Disease
The treatment of endodontic pathology follows careful
diagnostic procedures and a thorough review of a pa-
tient’s medical history. This chapter covers a wide range
of endodontic treatment modalities, from nonsurgical
root canal therapy to nonsurgical retreatment to surgi-
cal endodontic therapy and beyond. Furthermore, the
reader will nd information regarding postendodontic
restorative care. The chapter concludes with a review of
ethics and workplace safety issues.

121
Local Anesthesia
The foundation of endodontic treatment is the successful attainment of profound local
anesthesia. The selection of both the proper anesthetic solution and administration tech-
nique permits comfortable delivery of endodontic therapy for the practitioner as well as
patient. This section reviews several clinical anesthesia studies. A discussion of anesthetic
pharmacology can be found in chapter 5, and orofacial anatomy relevant to anesthesia can
be found in chapter 3. For those readers in search of a more comprehensive anesthesia
text, please review Successful Local Anesthesia for Restorative Dentistry and Endodontics
by Reader et al.
Maxillary anesthesia
Inltrations, rather than nerve blocks, are often effective when treating maxillary teeth.
In a recent study by Aggarwal et al (2011), no difference was noted between inltrations
and posterior superior alveolar blocks in their ability to anesthetize maxillary rst molars.
Furthermore, the addition of palatal anesthesia does not appear to increase anesthetic
success rates. In the same study by Aggarwal et al (2011), no difference was found between
buccal inltrations alone or when combined with palatal inltrations. Similarly, Guglielmo
et al
found that anesthesia success rates did not improve when palatal inltrations were
added; however, the duration of local anesthesia increased.
Based on the literature, both lidocaine and articaine provide successful anesthesia for
the treatment of maxillary teeth. Controversy exists as to whether one provides superior
anesthesia. Srinivasan et al found 4% articaine was superior to 2% lidocaine for posterior
teeth, whereas Evans et al found that articaine was superior in the anterior but not the
posterior regions. On the other hand, Kanaa et al (2012a) found no difference between the
anesthetics. Consequently, the selection of either anesthetic appears justied.
Mandibular anesthesia
For treatment of mandibular anterior and premolar teeth, inltration techniques often pro-
vide sufcient anesthesia. Dressman et al found that a single inltration of 4% articaine
in the mandibular premolar region provided successful pulpal anesthesia 80% to 87% of
the time, and an additional inltration increased success rates to 92% to 94%. Currie et
al
found that local inltration in the molar area works via a combined mental and incisive
nerve block.
The standard inferior alveolar nerve (IAN) block is the technique of choice for anesthesia
of mandibular posterior teeth. Goldberg et al found no advantage of the Gow-Gates or
Akinosi techniques over the standard approach. Malamed, on the other hand, suggested
that the Gow-Gates technique is superior to the standard block.
The choice of anesthetic appears to have little effect on IAN block success. McLean et al
found no differences between 3% mepivacaine, 2% lidocaine, or 4% prilocaine using this
technique. Fernandez et al additionally found no advantage of using 0.5% bupivacaine
over 2% lidocaine. However, Whitworth et al found that, in healthy teeth, 4% articaine is
more effective than 2% lidocaine in achieving anesthesia of the mandibular rst molar. Cau-
Treatment
of Endodontic
Disease
Local Anesthesia

122
Treatment of Endodontic Disease
8
tion must be exercised with its use though: Haas and Lennon as well as Gaffen and Haas
found a ve-fold increase in paresthesias when articaine was implemented for IAN blocks.
Similarly, Garisto et al reported that prilocaine and articaine used for dental local anesthe-
sia were associated with an increased risk of paresthesia at 7.3 and 3.6 times, respectively.
Just as anesthetic formulation has little effect on the success of the IAN block, the volume
of anesthetic also appears to have little effect on outcomes. In a study of 55 patients, Aggar-
wal et al (2012b) found that more profound anesthesia was achieved with 3.6 mL than with
1.8 mL of 2% lidocaine. In a similar, larger-scale study, Fowler and Reader found no differenc-
es between anesthetic volumes. Lastly, just as volume has no effect on anesthetic success,
injection speed does not inuence outcomes. Both Kanaa et al (2006) and Aggarwal et al
(2012a) found no differences in anesthetic success between fast and slow injections.
Recently, some authors have suggested that buccal inltration techniques may provide
anesthetic success rates similar to those obtained by IAN blocks for the treatment of man-
dibular molars. Corbett et al and Poorni et al reported no difference between inltrations
and IAN blocks with 4% articaine in their ability to achieve pulpal anesthesia. Recently, Ny-
degger et al found that though 4% articaine was statistically more effective than lidocaine or
prilocaine for buccal inltrations of the mandibular rst premolar in asymptomatic teeth, its
success rate was only 55%. These ndings suggest that the success of inltration anesthesia
is not predictable enough to support its use as a primary technique in the posterior mandible.
Adjunctive anesthetic techniques
When common anesthetic techniques fail to provide sufcient anesthesia for endodontic
therapy, adjunctive anesthetic techniques become necessary. Commonly cited reasons for
local anesthetic failure, summarized in Fig 8-1, include lower pH of inamed tissue, unsuc-
cessful techniques, inamed nerves with altered resting potentials and decreased excitabil-
ity thresholds, upregulation of anesthetic- and tetrodotoxin-resistant sodium channels, and
patient apprehension (Hargreaves and Keiser). Furthermore, difculty obtaining anesthesia
of mandibular molars with the standard IAN block is well documented in the literature. In
their text, Reader et al report that the success rate of the standard IAN block is between
15% and 57%. Consequently, supplementary anesthesia is often required.
Fig 8-1 Commonly cited reasons for anesthetic failures in dentistry
(Hargreaves and Keiser).
Lower pH of inamed tissues
Unsuccessful techniques
Altered resting potential in inamed nerves
Upregulation of anesthetic-resistant sodium
channels
Anxious patients

123
Nonsurgical Root Canal Therapy
Supplemental anesthetic techniques include inltrations, intraosseous anesthesia, peri-
odontal ligament (PDL) injections, and intrapulpal injections (Fig 8-2). Inltration, particular-
ly with articaine, may be the most effective supplemental anesthetic technique. According
to a randomized controlled trial by Kanaa et al (2012b), after a failed IAN block, additional
articaine inltrations provided successful anesthesia 84% of the time, intraosseous anes-
thesia 68% of the time, PDL injections 48% of the time, and repeat IAN blocks 32% of the
time. Rogers et al found that articaine was signicantly more effective than lidocaine when
given as a supplementary buccal inltration in symptomatic molars. Intraosseous anesthe-
sia, though effective, has been associated with an increase in heart rate (Wood et al), and
thus caution must be exercised with coexisting cardiac disease. Lastly, PDL injections do
not damage periodontal tissues (Lin et al)
and provide a safe alternative.
When all other techniques fail, intrapulpal anesthesia may be required. VanGheluwe and
Walton found that this technique is successful 92% of the time. Furthermore, the effect ap-
pears to be independent of solutions employed, namely saline or anesthetic. These results
suggest that anesthesia obtained by intrapulpal injection is due to intrapulpal pressure
rather than anesthetic pharmacology.
Nonsurgical Root Canal Therapy
Isolation
The American Association of Endodontists (AAE 2010) asserts that the use of rubber dams
during endodontic treatment is the standard of care. The aim of root canal therapy is to
render the root canal system free of microbes. The rubber dam is the only device capa-
ble of preventing contamination of the root canal system with oral ora during treatment
(Cochran et al). Furthermore, the rubber dam also aids in visualization during treatment
and reduces the risk of aspiration of irrigants or instruments (Ahmad). Lastly, survival of
endodontically treated teeth appears to be inuenced by the use of rubber dam isolation
during treatment. In a recent study, Lin et al found that the survival probability of endodon-
tically treated teeth was signicantly enhanced by rubber dam isolation.
Supplemental inltrations
Intraosseous anesthesia
PDL injections
Intrapulpal injections
Fig 8-2 Available adjunctive anesthetic techniques for endodontic
practice.

124
Treatment of Endodontic Disease
8
Magnication
The use of magnication, including that
provided by the surgical operating micro-
scope (Fig 8-3), is essential in the prac-
tice of endodontics. Microscopy serves
to aid the practitioner in the location of
normal anatomical structures during non-
surgical or surgical endodontic therapy
(Rubinstein and Kim), detection of cracks
or fractures (Slaton et al), removal of ob-
structions, and management of treatment
complications (Carr and Murgel). Given
the number of advantages provided by
the use of magnication during treat-
ment, the AAE position (2012) is that the
microscope is an integral and important
part of the performance of modern endo-
dontic techniques.
Access
The shape and location of the access preparation should reect pulpal anatomy. Krasner
and Rankow found that the cementoenamel junction (CEJ) provides the most consistent
landmark for the pulp chamber. Consequently, this landmark should be used when design-
ing the access preparation to reduce the risks of underextension and untreated anatomy
as well as overextension and perforation. Radiographic landmarks may also be useful to
successfully locate the pulp chamber. Robinson et al (1989a, 1989b) recommended bite-
wing radiography to assess coronal pulp anatomy. Recently, Azim et al found that cone
beam computed tomography (CBCT) images may be used for precise measurement of
pulp chamber landmarks prior to access cavity preparation.
Working length determination
Following coronal access, working lengths (WLs) for each canal can be determined by
radiographs, pre-existing CBCT scans, and electronic apex locators (EALs). Historically, ra-
diographs were the only means by which WL could be determined. The accuracy of WL
determination using this method varies by lm type and radiographic technique. Lozano
et al
found that conventional lm was more accurate than digital radiographs for WL de-
termination when smaller le sizes were used; however, with les larger than a no.15 K
le (0.15 mm in apical diameter), digital radiographs performed similarly. Forsberg found
that the paralleling technique more accurately determined WL than the bisecting angle
technique. New imaging techniques, namely CBCT, have been shown to provide accurate
WL measurements. Jeger et al found a high degree of correlation between WLs measured
with CBCTs and EALs.
Fig 8-3 Surgical operating microscope. Magni-
cation aids the practitioner in locating anatomi-
cal structures, detecting of cracks or fractures,
removing obstructions, and managing treatment
complications effectively.

125
Nonsurgical Root Canal Therapy
EALs, like radiographs, provide accu-
rate WL measurements. These instru-
ments were developed based on the
work of Suzuki, who showed that a con-
stant value of electrical resistance, 6.4
kilo-ohms, exists between the PDL and
the oral mucosa. Sunada conrmed Su-
zuki’s ndings in humans and applied
this principle to electronic apex determi-
nation. Kobayashi and Suda
developed
the Root ZX apex locator [J. Morita]
based on these ndings. Typical EALs
like the Root ZX measure impedance val-
ues that represent a ratio of resistances
(Kobayashi and Suda) (Fig 8-4).
Research indicates that these devices
are not only accurate but also useful un-
der many clinical conditions. Shabahang
et al found that EALs accurately locat-
ed the apical foramen 96% of the time.
However, Ounsi and Naaman found that
they were more useful to determine the
major diameter than the minor diameter. Their accuracy does not differ when used in vital or
necrotic cases (Dunlap et al), in the presence of apical root resorption (Goldberg et al), or in
the presence of apical periodontitis (Saatchi et al). Lastly, their accuracy is not affected by the
presence of solutions, including lidocaine, sodium hypochlorite, RC-Prep [Premier Dental],
ethylenediaminetetraacetic acid (EDTA), hydrogen peroxide, and chlorhexidine (Jenkins et
al). Their accuracy may be diminished when apical diameters are larger than 0.6 mm (Herrera
et al). Just as their accuracy is similar to radiographs, no differences in postoperative pain
were noted when WLs were measured with either method (Kara Tuncer and Gerek).
Not only are EALs an accurate means to measure WL, they provide a safe means for
WL determination in patients with pacemakers. Historically, EALs were considered unsafe
based on work by Wooley et al. However, recent research has failed to demonstrate an
effect of these units on pacemaker function or safety. An in vitro study by Garofalo et al
showed no effect on pacemaker function when EALs were directly connected to the units.
An in vivo study by Wilson et al further supported these results. Similarly, Idzahi et al
found
that these units are safe to use in patients with implantable cardiac debrillators (ICD). The
same study, however, indicated that electrosurgical units might alter ICD function.
Guide path maintenance and patency
With WLs established, a glide path to the apex must be maintained. Some authors ad-
vocate the maintenance of apical patency at the WL by passing small les through the
cementodentinal junction (CDJ). Vera et al (2012a) found that maintaining apical patency
decreased irrigant vapor lock in large canals by a signicant margin, thus increasing irrigant
Fig 8-4 A Root ZX electronic apex locator. These
units utilize impedance values to accurately mea-
sure root canal lengths. Their accuracy is not dimin-
ished by apical periodontitis, root resorption, or the
presence of irrigants.

126
Treatment of Endodontic Disease
8
Instrumentation
Endodontic instrumentation serves to remove debris (Dalton et al), permit irrigant penetra-
tion to the apex (Salzgeber and Brilliant), and prepare the canal for obturation (Schilder 1974).
Several root canal instrumentation techniques have been described in the literature. These
techniques include the step-down (Goerig et al),
passive step-back (Torabinejad), anticurva-
ture ling (Abou-Rass et al), balanced force (Roane et al 1985), and crown-down techniques
(Morgan and Montgomery) (Fig
8-6). According to Wu and Wes-
selink, all of these techniques
leave residual debris behind to
a similar degree. Consequently,
technique selection should be
based on operator experience
and preference.
In addition to the multitude of
instrumentation techniques de-
scribed, several types of instru-
ments, including both hand and
rotary instruments, are available
to practitioners. Hand instru-
ments are often fabricated out
of stainless steel, whereas rotary
efciency at the apex. In addition to an increase in irrigation efciency, Arias et al found
less postoperative pain when patency was maintained in nonvital teeth. Silva et al, on the
other hand, found no signicant differences in postoperative discomfort whether or not
patency was maintained.
Regardless of the effect of patency maintenance on irrigation efciency or postoperative
discomfort, traversing the apical foramen with small les may have a detrimental effect
on apical anatomy. Goldberg and Massone found that passing les through the periapex
caused transportation of the apical foramen regardless of le size or instrument type. Ador-
no et al demonstrated a signicant increase in the presence of apical cracks as a result of
foraminal enlargement. Because of such demonstrable damage, one must carefully consid-
er the practice of patency maintenance. Arguments both for and against the maintenance
of apical patency are summarized in Fig 8-5.
Fig 8-5 Positive and negative ndings associated with the maintenance of api-
cal patency by passing instruments through the apical foramen.
Improves efciency
of irrigation at the
apex
May decrease post-
operative pain
Causes transpor-
tation of the apical
foramen
Increases the num-
ber of apical cracks
Positives
Negatives
Fig 8-6 Commonly described instrumentation techniques
and the authors to whom they are attributed.
Step-down
Passive step-back
Anticurvature ling
Balanced force
Crown-down
Goerig
Torabinejad
Abou-Rass
Roane
Morgan and Montgomery

127
Nonsurgical Root Canal Therapy
Instrumentation of the apical portion of the canal is often described with respect to the
master apical le (MAF). Salzgeber and Brilliant found that a minimum MAF size of a no.
30 K le allowed penetration of irrigants to the apex. Other authors, including Mickel et
al, have suggested that the MAF size should reect the size of the apex. They found that
by using a crown-down technique to assess apical size, followed by an increase in three
le sizes to nal instrumentation, greater bacterial reduction was noted than if only one le
size greater than the initial was selected. Similarly, Saini et al found that outcomes were
signicantly improved when the MAF was three sizes larger than the initial apical size and
that further enlargement did not provide any additional benet. Consequently, absolute
master apical le size recommendations may be inappropriate.
Instrumentation, though effective in shaping the root canal system and removing debris,
produces a smear layer. Mader et al found that the smear layer consisted of two conuent
components: the smeared layer on the surface of the canal wall and debris packed in den-
tinal tubules. McComb et al found that all standard instrumentation techniques produced
this layer. Controversy exists as to whether or not this layer needs to be removed prior to
instruments are frequently constructed from nickel titanium (NiTi) alloys (Hargreaves et al).
NiTi alloys cycle through several temperature-dependent crystalline structures, including
the stiffer austenite phase, the intercrystalline R phase, and the more exible low-tempera-
ture martensite phase (Shen et al 2013). Newer instruments are fabricated from controlled
memory (CM) wire, a heat-treated NiTi substance in which the austenite nish temperature
is higher than body temperature, thus keeping the instrument in the more exible mar-
tensite and R phases (Shen et al 2013). This technology improves NiTi fatigue resistance
over conventional instruments (Shen et al 2011). According to Dalton et al, both hand and
rotary instruments reduce intracanal bacterial levels to a similar degree. However, Short et
al found that rotary instruments remain better centered in the root canal system.
With instruments and techniques selected, cleaning and shaping of the entire root canal
system can commence. Instrumentation of the coronal portion of the canal, referred to
as coronal aring, has several functions (Fig 8-7). It provides straight-line access to the
apical portion of the canal (Schroeder et al), and allows the apical foramen to be reached
more consistently when read with EALs (Ibarrola et al). Furthermore, Roland et al found
that prearing decreases the incidence of rotary instrument separation. However, this pro-
cess leads to a change in WL measurements; although, according to Schroeder et al, this
change is clinically insignicant.
Fig 8-7 Functions of coronal aring.
Provide
straight-line
access to the
apical portion
of the canal
Allow the
apical fora-
men to be
reached more
consistently
with EALs
Decrease
the incidence
of rotary
instrument
separation

128
Treatment of Endodontic Disease
8
Sodium hypochlorite is the most commonly used endodontic irrigant, as it fullls many
of Zehnder’s criteria. Its properties are summarized in Fig 8-9. Baumgartner and Mader
found that sodium hypochlorite dissolves necrotic tissue and the organic component of the
smear layer, while Rosenfeld et al found that it dissolves vital tissue. Sodium hypochlorite
effectively eradicates endodontic pathogens, including planktonic bacteria (Haapasalo et
al), those in established biolms (Del Carpio-Perochena et al), as well as bacteria that have
penetrated into the dentinal tubules up to 0.3 mm (Wong and Cheung).
root canal obturation. Those who advocate for its removal include Taylor et al, who found
less coronal leakage with its removal, and Sen et al, who found that the smear layer blocks
the disinfecting properties of both sodium hypochlorite and chlorhexidine. Those who rec-
ommend leaving it intact include Madison and Krell,
who found that the layer did not affect
an apical seal, and Clark-Holke et al and Drake et al, who found more bacteria with the
layer removed.
Irrigation
Endodontic instrumentation alone cannot render root canal systems free of debris. Ac-
cording to Peters et al, endodontic instrumentation leaves 35% of canal walls untouched.
Furthermore, the existence of isthmuses between canals and lateral canal anatomy has
been well documented in the literature (Senia et al), and often, instruments do not reach
these areas. Consequently, irrigation is necessary to ush the root canal system of debris
and eradicate microbes. According to a review by Zehnder, the ideal irrigant possesses
broad antimicrobial properties, is highly effective against anaerobic and facultative micro-
organisms, dissolves both vital and necrotic tissue, inactivates lipopolysaccharide (LPS),
and either prevents the formation of the smear layer during instrumentation or dissolves it
once formed. Ideal irrigant properties are summarized in Fig 8-8.
Broad
antimicrobial
properties
Either
prevents
formation of
the smear
layer or
dissolves it
once formed
Inactivates
LPS
Highly effec-
tive against
anaerobic and
facultative
organisms
Dissolves
both vital
and necrotic
tissue
Fig 8-8 Properties of the ideal endodontic irrigant. Though many irrigants possess one or several
of these capabilities, no one irrigant available today fullls all criteria (Zehnder).

129
Nonsurgical Root Canal Therapy
Most AAE members report using sodium hypochlorite at concentrations of 5.25% or
greater (Dutner et al). Several literature justications exist to support the use of this concen-
tration. Hand et al
found that 5.25% sodium hypochlorite was most effective at dissolving
necrotic tissue, and Senia et al found it was the best concentration for removing vital tissue.
Harrison et al found that this concentration was safe for clinical use and did not increase
postoperative pain. Morgental et al
found that 5.25% sodium hypochlorite was more effec-
tive than either chlorhexidine or QMix irrigation solution [Dentsply]—a product containing
chlorhexidine, EDTA, and surfactant—at eradicating Enterococcus faecalis. Despite reports
on concentration effectiveness, it is clear that great variation exists in sodium hypochlo-
rite concentrations obtained commercially, and less free chlorine is often available than
is reported on the label (van der Waal et al). Consequently, practitioners must pay close
attention to the products they purchase.
Although sodium hypochlorite effectively disinfects the root canal system and dissolves
tissue, it lacks the ability to dissolve the mineralized component of the smear layer. As a
result, many practitioners use chelating solutions as part of their irrigation protocols. EDTA
chelates calcium ions, effectively targeting dental hard tissue debris (Calt and Serper). Calt
and Serper found that a 1-minute rinse with EDTA removed the smear layer in its entirety,
although a 10-minute application resulted in excessive dentin erosion. Additionally, Dai et
al found that QMix was as effective as 17% EDTA in removing the smear layer. Consequent-
ly, practitioners now possess several choices in demineralization solutions.
Caution must be exercised when both EDTA and sodium hypochlorite are used in the
same procedure, as their combined use can result in excessive demineralization of tooth
structure. Qian et al found that sodium hypochlorite, if used as a nal irrigant after EDTA,
caused marked erosion of root canal dentin. Baumgartner and Mader found that when both
solutions were alternated, excessive loss of intertubular dentin occurred. Furthermore, when
solutions are combined, EDTA can reduce the efcacy of sodium hypochlorite. Clarkson et al
found that the active chlorine content of sodium hypochlorite was reduced when mixed with
EDTA. Consequently, practitioners must design their irrigation protocols carefully.
• Dissolves necrotic tissue
• Dissolves vital tissue
Removes the organic component of the smear layer
• Kills planktonic bacteria
Kills bacteria in established biolms
• Kills bacteria in dentinal tubules
Sodium
hypochlorite
Fig 8-9 Properties of sodium hypochlorite that make it an effective endodontic irrigant.

130
Treatment of Endodontic Disease
8
In addition to sodium hypochlorite and EDTA, chlorhexidine gluconate (CHX), a biguanide,
has gained popularity as an endodontic irrigant. Jeansonne and White recommended its use
in cases of allergy to sodium hypochlorite or with open apices where sodium hypochlorite ex-
trusion would pose a risk. They found it was as effective as 5.25% sodium hypochlorite in terms
of its antibacterial activity. Cook et al found that a 10-minute CHX soak was the most effective
means to eliminate E faecalis from the root canal system. CHX also possesses the property
of substantivity; it binds to dentin, allowing its antibacterial activity to persist for as many as
48 days after exposure (Baca et al).
Despite these overwhelmingly positive ndings, CHX has
several drawbacks. First, it lacks the ability to dissolve organic substances, namely vital and ne-
crotic tissue (Okino et al). Second, as Basrani et al found, it reacts with sodium hypochlorite to
form a red-brown, carcinogenic precipitate called parachloroaniline (Fig 8-10). This precipitate
has the ability to occlude dentinal tubules (Bui et al). Recent research by Barbin et al suggested
that this precipitate may be present in solutions of CHX alone and with its use in combination
with calcium hydroxide. Consequently, CHX should be used cautiously.
CHX
(liquid)
Parachloroaniline
(solid)
Sodium
hypochlorite
(liquid)
Fig 8-10 The chemical reaction between CHX and sodium hypochlorite solutions to produce the
red-brown precipitate parachloroaniline (Basrani et al).
Adjunctive irrigation techniques
Just as several irrigant solutions are available to practitioners, so are adjunctive irrigation
techniques, including passive ultrasonic activation, sonic activation, photodynamic thera-
py, and the EndoVac [Kerr] irrigation system (Fig 8-11). At this time, 45% of AAE members
report using adjunctive irrigation techniques (Dutner et al).
All techniques appear to offer
improvements in disinfection, debridement, or both.
The EndoVac system and photodynamic therapy offer improvements in debridement
or bacterial reduction, but not both. According to Nielsen and Baumgartner, the EndoVac
system offers signicantly better debridement than needle irrigation at a level 1 mm from
the apex, most likely because it improves delivery of the irrigant to the apex (Munoz and
Camacho-Cuadra). It may also improve sealer penetration at the apex (Kara Tuncer and
Unal). Despite these improvements, Beus et al found that the EndoVac offers no improve-
ment in bacterial reduction. Photodynamic therapy, according to Chrepa et al, is effective
at reducing microbial loads; however, limited clinical studies exist.

131
Nonsurgical Root Canal Therapy
Passive ultrasonic irrigation (PUI) improves both debridement and disinfection. Further-
more, according to Jensen et al, sonic activation offers debridement equivalent to PUI. By
creating acoustic streaming patterns (Ahmad et al), PUI improves the cleanliness of both
the main canal and isthmuses (Gutarts et al). It is more effective than syringe irrigation in
removing debris from depressions in the canal space (Malki et al). PUI is also as effective as
a nal rinse with CHX in eliminating bacteria (Beus et al). Grundling et al, however, assert
that bacterial elimination during PUI is a function of the irrigant rather than the activation.
Despite the improvements PUI has over standard needle irrigation, Liang et al found no
signicant differences in periapical healing when this technique was employed.
Single-visit therapy versus multiple-visit therapy
Endodontic therapy can be completed in
a single visit or over the course of multiple
visits. Arguments both for and against sin-
gle-visit endodontic therapy often focus on
one of three factors (Fig 8-12): the eradication
of bacteria, the effect on postoperative pain,
and the effect on prognosis. A thorough re-
view of the literature reveals that both single-
and multiple-visit treatment can be supported
based on those three subjects. Consequently,
treatment either in a single visit or in multiple
visits is justiable, and the choice lies at the
discretion of the practitioner. Vela et al found
that though many patients would prefer sin-
gle-visit therapy, most would follow their den-
tist’s recommendation for two-visit therapy if
an improved outcome was expected.
While several reports indicate that the root
canal system cannot be reliably cleaned of
Fig 8-11 Commonly researched adjunctive irrigation techniques. These offer improve-
ments in debridement, disinfection, or both.
Passive
ultrasonic
activation
Photodynamic
therapy
Sonic
activation
EndoVac
irrigation
system
Fig 8-12 Three factors used to justify single-
visit endodontic therapy versus multiple-
visit therapy. Positions supporting either
treatment can be defended based on any of
these considerations.
Inuence on
prognosis
Effect on
post-treatment
pain
Capacity to
disinfect

132
Treatment of Endodontic Disease
8
bacteria in a single visit without use of an interappointment, intracanal medicament, other
research found that disinfection was not improved with medicaments. Sjogren et al (1991)
found that thorough disinfection of the root canal system required 7 days of treatment with
calcium hydroxide (CH), and bacteria were not sufciently eliminated after 10 minutes or
24 hours of exposure to the medicament. Law and Messer found that interappointment
treatment with CH increased the number of root canals with undetectable levels of bac-
teria. Xavier et al interestingly found no difference in bacterial reduction in single versus
multiple visits but found that two-visit treatment with CH eliminated more LPS than root
canal therapy completed in a single visit.
On the other hand, several studies found that two-visit therapy does not increase bacterial
disinfection. Peters and Wesselink found that, in two-visit therapy, bacterial regrowth was
not prevented by interappointment CH, and no further disinfection was evident. Vera et al
(2012b) found that, after two-visit treatment with CH dressing, bacteria were still evident in
the isthmuses and other canal ramications but not within the main canal or dentinal tubules.
Pain outcomes are also cited as reasons both for and against single-visit treatment.
Like those for bacterial reduction, literature justications exist to support either position.
Soltanoff and Figini et al found that patients experienced more pain following single-visit
treatment. Conversely, both Roane et al (1983) and Eleazer and Eleazer found more pain
and more frequent are-ups in multiple-visit treatment. Between these two extremes are
authors, namely Pekruhn as well as Walton and Fouad, who found no differences in pain
experienced by either group.
The last area often discussed in reference to single- and multiple-visit therapy is the
effect on prognosis. Like bacterial reduction and pain, evidence for and against single-visit
treatment based on prognosis is present in the literature. Trope et al found that two-visit
therapy improved outcomes in necrotic cases. Similarly, Peters and Wesselink found a ten-
dency for increased healing when two-visit endodontic therapy was performed, though re-
sults were not statistically signicant. However, several studies rebuff these ndings. Stud-
ies by Penesis et al, Molander et al, and Paredes-Vieyra and Enriquez and a meta-analysis
by Su et al found no difference in outcomes between teeth treated in a single visit or over
multiple visits.
Intracanal medicaments
If the decision to perform multiple-visit root canal therapy is made, the use of an intracanal
medicament is recommended. The purpose of the medicament is to aid in disinfection
and prevent recolonization of the root canal space with bacteria. Bystrom and Sundqvist
demonstrated that, without the use of an intracanal medicament, canals rendered bacteria
free during instrumentation exhibited culture reversals. Several medications are available
to practitioners including CH, CHX gel, and antibiotic pastes. For further information re-
garding intracanal antibiotic pastes, please refer to the section in this chapter on regener-
ative endodontics.
CH has a basic pH between 11 and 12 and diffuses into dentinal tubules, causing an in-
crease in the pH of outer root dentin after 2 to 3 weeks (Nerwich et al). These effects do not
extend into cementum or the adjacent PDL space, indicating that the cementum may act
as a buffer (Tronstad et al). The most effective means of delivering CH into the root canal
space is the lentulo spiral, followed by injection and K les (Sigurdsson et al). CH eliminates

133
Nonsurgical Root Canal Therapy
the majority of bacterial species in the root canal system, though some anaerobic species
(Sjogren et al 1991) and E faecalis may be resistant to its effects (Siren et al). In addition to
its antibacterial effects, CH reduces the cytotoxic response to LPS by destroying its lipid A
moiety (Safavi and Nichols). CH may also dissolve tissue remaining in the root canal space
after instrumentation (Hasselgren et al). Furthermore, it is the favored intracanal medica-
ment for regenerative endodontic therapy as it is less cytotoxic than antibiotic pastes or
CHX against apical papilla stem cells (Ruparel et al). Interestingly, the combination of CH
and omeprazole resulted in superior repair of rat periapical lesions when compared with
conventional CH (Wagner et al).
Despite its positive effects, care must be exercised with CH as it may negatively impact
the physical properties of both teeth and root canal lling materials. Blomlof et al
demon-
strated that long-term applications could cause PDL necrosis. Additionally, Andreasen et
al found that long-term CH decreased dentinal fracture resistance. CH can also negatively
impact surrounding anatomical structures. Care should be taken to prevent its overexten-
sion into tissue spaces as it has been associated with devastating tissue necrosis (Lindgren
et al) and paresthesia (Ahlgren et al). Lastly, CH may inuence obturation because it inhibits
setting of eugenol-based sealers (Margelos et al). Remaining CH can affect the penetration
of sealers into dentinal tubules and increase apical leakage (Kim and Kim). Consequently,
its thorough removal is imperative prior to obturation. Passive ultrasonic irrigation (Capar
et al) or rotary instrumentation (Kenee et al) are more effective than syringe irrigation at
removing CH from the canal system. Peracetic acid was found to remove more CH than
sodium hypochlorite or EDTA (Sagsen et al).
CHX gel is often suggested as an alternative to CH. Like CH, it possesses broad anti-
bacterial abilities. Wang et al found that 2% CHX gel is an effective root canal disinfectant.
It is effective against gram-positive and gram-negative bacteria, both aerobic and an-
aerobic species, and fungi (Waltimo et al). Furthermore, it exhibited greater antibacterial
activity against E faecalis than CH (Buck et al). Like CH, CHX also reduces intracanal LPS
(Oliveira et al). Lastly, CHX alters periapical healing responses. Not only does its application
between appointments prevent the increase of pro-inammatory and immunoregulatory
cytokines (Tavares et al), but more favorable healing of periapical lesions was noted with
CHX application than with CH (Leonardo et al). Properties of CH and CHX are summarized
in Fig 8-13.
CH CHX
Demonstrates broad microbial
properties
Eradicates LPS
Dissolves tissue
Provides favorable cytotoxicity
prole toward apical papilla
stem cells
Demonstrates broad antimicro-
bial properties
Eradicates LPS
Reduces pro-inammatory cyto-
kine expression in the periapex
Improved periapical healing
over CH
Fig 8-13 Properties associated with CH and CHX intracanal medicaments that make them useful for
endodontic therapy.

134
Treatment of Endodontic Disease
8
Filling techniques with this material include lateral condensation and vertical condensa-
tion. Neither leakage nor outcomes appear to be inuenced by lling technique. Jacobson
et al found that, though teeth obturated by lateral condensation leaked microbes faster
than those lled by vertical condensation, no differences in the numbers of teeth that
leaked were noted. No differences were noted in voids between the two techniques (Read-
er et al). Lastly, no differences in outcomes were noted between teeth treated with either
technique (Peng et al).
Resilon [Resilon Research] offers an alternative to GP llings; it is a polyester core material
used with a resin-based sealer (Orstavik). Though previous research suggested that Resilon
offered superior lls to GP (Teixeira et al), other work suggested that lls offer no improve-
ments over GP in terms of leakage (Biggs et al) or movement into three-dimensional anatomy
(Karr et al). Although Resilon was thought to create a “mono block” lling material whereby
the sealer bonded both to dentin and to the lling material (Teixeira et al), research does not
support these claims (Gesi et al).
Carrier-based systems provide an alternative to GP, though the lling quality they provide
may be inferior to other techniques. These are marketed as offering signicant time savings
and ease over other obturation systems. However, research shows that the carrier-based
lling materials result in lls that leak signicantly more than laterally or vertically condensed
GP (Baumgardner et al).
Obturation
Following cleaning and shaping of the root canal system, placement of a three-
dimensionally adapted lling is indicated (Schilder 1967). Several materials and techniques
are available to accomplish this goal. Traditional root canal lling material is composed of
gutta-percha (GP), described in Fig 8-14. GP is closely related to rubber and is a naturally
occurring polymer of isoprene (Goodman et al 1974). GP cones are composed of zinc
oxide (65%), GP (20%), and other materials including waxes, resins, and metals (Goodman
et al 1974). GP is in its beta crystalline state when in cone form and undergoes a change
to the alpha crystalline state when heated between 42ºC and 49ºC (Goodman et al 1981).
GP designed for thermoplastic applications shrinks quickly and extensively upon cooling
and differs signicantly between brands (Lottanti et al). As GP is chemically close to rubber,
care should be used in patients with a severe type I allergy to latex (Costa et al, Orstavik).
Trans-isoprene, chemically related to natural rubber latex
Cones are composed of 65% zinc oxide, 20% GP, and 15% waxes,
resins, and metals
Commercially available in the beta crystalline phase
Changes to alpha crystalline phase on heating
GP
Fig 8-14 Common properties of GP obturation materials.

135
Nonsurgical Root Canal Therapy
No matter which technique is used to obturate the root canal system, sealer is an essential
component (Marshall and Massler). Several sealers are commercially available, including euge-
nol-based products, resin/epoxy–based products, glass-ionomer–based products, silicone-based
products, and CH-based products. Recently, sealers-based on mineral trioxide aggregate (MTA)
have become available (Vitti et al). Sealers are often compared in terms of biocompatibility, ease
of use, antibacterial activity, adherence to dentin, and other properties (Orstavik). It behooves
the practitioner to select an appropriate product based on these properties and one’s personal
preferences. No matter which sealer is selected, placement can be completed with K les, lentulo
spirals, or GP cones with no effect on ll quality (Wiemann and Wilcox).
Instrumentation and obturation should terminate at the CDJ (Ricucci), as overinstrume-
nation and overlling cause periapical inammation (Seltzer et al). Obturation materials, in-
cluding particulate GP, have been associated with robust inammatory responses (Sjogren
et al 1995). Though Augsburger and Peters found that sealers expressed into the periapical
tissues resorb radiographically over time, care should be taken to avoid doing so because
these materials have been associated with chronic inammation (Seltzer et al), sinus infec-
tion with Aspergillus (Giardino et al), and paresthesia (Gonzalez-Martin et al).
Temporary restorations
Following completion of root canal therapy, and prior to placement of the denitive coronal
restoration, temporary restorative materials are used to seal the coronal access, thus pre-
venting contamination of the root canal lling with oral microbes (Swanson and Madison).
Several temporary lling materials are commercially available, including but not limited to
Cavit [3M ESPE], Intermediate Restorative Material (IRM) [Dentsply], and glass-ionomer ce-
ments. In a study by Turner et al,
all of the aforementioned materials adequately prevented
microleakage. For adequate prevention of leakage with Cavit, Webber et al found that a
3.5-mm-thick seal was necessary. Lamers et al showed that Cavit leaked after 42 days, sup-
porting its use only in the short term. Barthel et al showed that both Cavit and IRM leaked
signicantly more than glass ionomers. Consequently, glass ionomers may be the materials
of choice for temporary restorations.
Eugenol is found in several temporary restorations and in root canal cements. This clove
oil derivative exhibits several biologic activities worth mentioning (Fig 8-15). Eugenol alters
neurotransmission (Kozam) via increased potassium permeability and decreased sodium
inux in nerves, thus decreasing the rate at which action potentials re (Trowbridge et al).
Furthermore, eugenol blocks the expression of neuropeptides associated with inamma-
tion (Trowbridge). Lastly, it decreases the vasoconstriction response to epinephrine (Mjor).
Alters neurotransmission by increasing potassium permeability and
decreasing sodium inux
Blocks neuropeptide expression
Decreases the vascular response to epinephrine
Eugenol
Fig 8-15 Commonly reported properties of eugenol.

136
Treatment of Endodontic Disease
8
Nonsurgical Retreatment
Nonsurgical retreatment is indicated when symptoms or radiographic pathology are evi-
dent in endodontically treated teeth. Factors associated with persistent or recurrent apical
periodontitis include coronal leakage (Ricucci and Siqueira), intraradicular infection (Vieira
et al), extraradicular infection, untreated canal anatomy, fractures, foreign body reactions,
and true cystic lesions (Nair). With proper case selection, the prognosis of nonsurgical
retreatment is favorable (Salehrabi and Rotstein). Despite the often-favorable outcomes,
many general dentists prefer to pursue extraction of teeth with recurrent apical periodon-
titis in favor of implant placement (Azarpazhooh et al). Consequently, specialists must edu-
cate their referral base regarding both treatment possibilities and their prognosis.
Post removal
Posts are often the rst obstacles encountered in a retreatment case. According to John-
son et al, 16 minutes of ultrasonic vibration is an effective means to remove metal posts.
In addition to their efcacy, ultrasonics are safe for use, even in patients with pacemaker
units (Gomez et al). Care must be taken, though because ultrasonics produce signicant
amounts of heat and are thus capable of causing bony damage. Dominici et al found that
temperature increases approaching 10ºC occurred in as little as 15 seconds without irriga-
tion. Thankfully, Huttula et al found that the use of an irrigant maintained the temperature
well below that which could cause bony damage. The removal of ber posts can be accom-
plished most effectively with either burs or ultrasonic vibration, though these methods are
slower than commercially available kits (Lindemann et al).
Gutta-percha removal
The ability of retreatment techniques to remove GP llings depends not only on the com-
position of the sealer (Neelakantan et al, Hess et al) but also the type of instruments used
(Xu et al). Retreatment of GP root canal lings often employs the use of solvents. Kaplowitz
found that of ve tested solvents, chloroform was the only solvent able to completely
dissolve the GP. Not only is chloroform safe for both patients (Chutich et al) and providers
(McDonald and Vire) if used properly, it also aids in disinfection of the root canal space
(Edgar et al). Ferreira et al found that the combination of chloroform and either rotary or
hand instrumentation produced similarly clean canals; however, rotary methods were sig-
nicantly faster. Care must be taken no matter which method is chosen as both can cause
defects in canal walls (Shemesh et al).
“Russian Red” removal
A combination of formaldehyde and resorcinol used in conjunction with a sodium hydroxide
catalyst produces the paste-like lling material often referred to as “Russian Red.” These
components solidify following their introduction into the root canal space with an appropri-
ate instrument. Retreatment of Russian Red is often difcult, as the llings produced by this
material range in consistency from sap-like to rock hard (Schwandt and Gound). Unlike GP
llings, solvents do not affect Russian Red endodontic pastes. Vranas et al found that both

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8Treatment of Endodontic DiseaseThe treatment of endodontic pathology follows careful diagnostic procedures and a thorough review of a pa-tient’s medical history. This chapter covers a wide range of endodontic treatment modalities, from nonsurgical root canal therapy to nonsurgical retreatment to surgi-cal endodontic therapy and beyond. Furthermore, the reader will nd information regarding postendodontic restorative care. The chapter concludes with a review of ethics and workplace safety issues. 121Local AnesthesiaThe foundation of endodontic treatment is the successful attainment of profound local anesthesia. The selection of both the proper anesthetic solution and administration tech-nique permits comfortable delivery of endodontic therapy for the practitioner as well as patient. This section reviews several clinical anesthesia studies. A discussion of anesthetic pharmacology can be found in chapter 5, and orofacial anatomy relevant to anesthesia can be found in chapter 3. For those readers in search of a more comprehensive anesthesia text, please review Successful Local Anesthesia for Restorative Dentistry and Endodontics by Reader et al. Maxillary anesthesiaInltrations, rather than nerve blocks, are often effective when treating maxillary teeth. In a recent study by Aggarwal et al (2011), no difference was noted between inltrations and posterior superior alveolar blocks in their ability to anesthetize maxillary rst molars. Furthermore, the addition of palatal anesthesia does not appear to increase anesthetic success rates. In the same study by Aggarwal et al (2011), no difference was found between buccal inltrations alone or when combined with palatal inltrations. Similarly, Guglielmo et al found that anesthesia success rates did not improve when palatal inltrations were added; however, the duration of local anesthesia increased.Based on the literature, both lidocaine and articaine provide successful anesthesia for the treatment of maxillary teeth. Controversy exists as to whether one provides superior anesthesia. Srinivasan et al found 4% articaine was superior to 2% lidocaine for posterior teeth, whereas Evans et al found that articaine was superior in the anterior but not the posterior regions. On the other hand, Kanaa et al (2012a) found no difference between the anesthetics. Consequently, the selection of either anesthetic appears justied. Mandibular anesthesiaFor treatment of mandibular anterior and premolar teeth, inltration techniques often pro-vide sufcient anesthesia. Dressman et al found that a single inltration of 4% articaine in the mandibular premolar region provided successful pulpal anesthesia 80% to 87% of the time, and an additional inltration increased success rates to 92% to 94%. Currie et al found that local inltration in the molar area works via a combined mental and incisive nerve block.The standard inferior alveolar nerve (IAN) block is the technique of choice for anesthesia of mandibular posterior teeth. Goldberg et al found no advantage of the Gow-Gates or Akinosi techniques over the standard approach. Malamed, on the other hand, suggested that the Gow-Gates technique is superior to the standard block. The choice of anesthetic appears to have little effect on IAN block success. McLean et al found no differences between 3% mepivacaine, 2% lidocaine, or 4% prilocaine using this technique. Fernandez et al additionally found no advantage of using 0.5% bupivacaine over 2% lidocaine. However, Whitworth et al found that, in healthy teeth, 4% articaine is more effective than 2% lidocaine in achieving anesthesia of the mandibular rst molar. Cau-Treatment of Endodontic DiseaseLocal Anesthesia 122Treatment of Endodontic Disease8tion must be exercised with its use though: Haas and Lennon as well as Gaffen and Haas found a ve-fold increase in paresthesias when articaine was implemented for IAN blocks. Similarly, Garisto et al reported that prilocaine and articaine used for dental local anesthe-sia were associated with an increased risk of paresthesia at 7.3 and 3.6 times, respectively. Just as anesthetic formulation has little effect on the success of the IAN block, the volume of anesthetic also appears to have little effect on outcomes. In a study of 55 patients, Aggar-wal et al (2012b) found that more profound anesthesia was achieved with 3.6 mL than with 1.8 mL of 2% lidocaine. In a similar, larger-scale study, Fowler and Reader found no differenc-es between anesthetic volumes. Lastly, just as volume has no effect on anesthetic success, injection speed does not inuence outcomes. Both Kanaa et al (2006) and Aggarwal et al (2012a) found no differences in anesthetic success between fast and slow injections. Recently, some authors have suggested that buccal inltration techniques may provide anesthetic success rates similar to those obtained by IAN blocks for the treatment of man-dibular molars. Corbett et al and Poorni et al reported no difference between inltrations and IAN blocks with 4% articaine in their ability to achieve pulpal anesthesia. Recently, Ny-degger et al found that though 4% articaine was statistically more effective than lidocaine or prilocaine for buccal inltrations of the mandibular rst premolar in asymptomatic teeth, its success rate was only 55%. These ndings suggest that the success of inltration anesthesia is not predictable enough to support its use as a primary technique in the posterior mandible. Adjunctive anesthetic techniquesWhen common anesthetic techniques fail to provide sufcient anesthesia for endodontic therapy, adjunctive anesthetic techniques become necessary. Commonly cited reasons for local anesthetic failure, summarized in Fig 8-1, include lower pH of inamed tissue, unsuc-cessful techniques, inamed nerves with altered resting potentials and decreased excitabil-ity thresholds, upregulation of anesthetic- and tetrodotoxin-resistant sodium channels, and patient apprehension (Hargreaves and Keiser). Furthermore, difculty obtaining anesthesia of mandibular molars with the standard IAN block is well documented in the literature. In their text, Reader et al report that the success rate of the standard IAN block is between 15% and 57%. Consequently, supplementary anesthesia is often required. Fig 8-1 Commonly cited reasons for anesthetic failures in dentistry (Hargreaves and Keiser).Lower pH of inamed tissuesUnsuccessful techniquesAltered resting potential in inamed nervesUpregulation of anesthetic-resistant sodium channelsAnxious patients 123Nonsurgical Root Canal TherapySupplemental anesthetic techniques include inltrations, intraosseous anesthesia, peri-odontal ligament (PDL) injections, and intrapulpal injections (Fig 8-2). Inltration, particular-ly with articaine, may be the most effective supplemental anesthetic technique. According to a randomized controlled trial by Kanaa et al (2012b), after a failed IAN block, additional articaine inltrations provided successful anesthesia 84% of the time, intraosseous anes-thesia 68% of the time, PDL injections 48% of the time, and repeat IAN blocks 32% of the time. Rogers et al found that articaine was signicantly more effective than lidocaine when given as a supplementary buccal inltration in symptomatic molars. Intraosseous anesthe-sia, though effective, has been associated with an increase in heart rate (Wood et al), and thus caution must be exercised with coexisting cardiac disease. Lastly, PDL injections do not damage periodontal tissues (Lin et al) and provide a safe alternative. When all other techniques fail, intrapulpal anesthesia may be required. VanGheluwe and Walton found that this technique is successful 92% of the time. Furthermore, the effect ap-pears to be independent of solutions employed, namely saline or anesthetic. These results suggest that anesthesia obtained by intrapulpal injection is due to intrapulpal pressure rather than anesthetic pharmacology. Nonsurgical Root Canal TherapyIsolationThe American Association of Endodontists (AAE 2010) asserts that the use of rubber dams during endodontic treatment is the standard of care. The aim of root canal therapy is to render the root canal system free of microbes. The rubber dam is the only device capa-ble of preventing contamination of the root canal system with oral ora during treatment (Cochran et al). Furthermore, the rubber dam also aids in visualization during treatment and reduces the risk of aspiration of irrigants or instruments (Ahmad). Lastly, survival of endodontically treated teeth appears to be inuenced by the use of rubber dam isolation during treatment. In a recent study, Lin et al found that the survival probability of endodon-tically treated teeth was signicantly enhanced by rubber dam isolation. Supplemental inltrationsIntraosseous anesthesiaPDL injectionsIntrapulpal injectionsFig 8-2 Available adjunctive anesthetic techniques for endodontic practice. 124Treatment of Endodontic Disease8MagnicationThe use of magnication, including that provided by the surgical operating micro-scope (Fig 8-3), is essential in the prac-tice of endodontics. Microscopy serves to aid the practitioner in the location of normal anatomical structures during non-surgical or surgical endodontic therapy (Rubinstein and Kim), detection of cracks or fractures (Slaton et al), removal of ob-structions, and management of treatment complications (Carr and Murgel). Given the number of advantages provided by the use of magnication during treat-ment, the AAE position (2012) is that the microscope is an integral and important part of the performance of modern endo- dontic techniques. AccessThe shape and location of the access preparation should reect pulpal anatomy. Krasner and Rankow found that the cementoenamel junction (CEJ) provides the most consistent landmark for the pulp chamber. Consequently, this landmark should be used when design-ing the access preparation to reduce the risks of underextension and untreated anatomy as well as overextension and perforation. Radiographic landmarks may also be useful to successfully locate the pulp chamber. Robinson et al (1989a, 1989b) recommended bite-wing radiography to assess coronal pulp anatomy. Recently, Azim et al found that cone beam computed tomography (CBCT) images may be used for precise measurement of pulp chamber landmarks prior to access cavity preparation. Working length determinationFollowing coronal access, working lengths (WLs) for each canal can be determined by radiographs, pre-existing CBCT scans, and electronic apex locators (EALs). Historically, ra-diographs were the only means by which WL could be determined. The accuracy of WL determination using this method varies by lm type and radiographic technique. Lozano et al found that conventional lm was more accurate than digital radiographs for WL de-termination when smaller le sizes were used; however, with les larger than a no.15 K le (0.15 mm in apical diameter), digital radiographs performed similarly. Forsberg found that the paralleling technique more accurately determined WL than the bisecting angle technique. New imaging techniques, namely CBCT, have been shown to provide accurate WL measurements. Jeger et al found a high degree of correlation between WLs measured with CBCTs and EALs. Fig 8-3 Surgical operating microscope. Magni-cation aids the practitioner in locating anatomi-cal structures, detecting of cracks or fractures, removing obstructions, and managing treatment complications effectively. 125Nonsurgical Root Canal TherapyEALs, like radiographs, provide accu-rate WL measurements. These instru-ments were developed based on the work of Suzuki, who showed that a con-stant value of electrical resistance, 6.4 kilo-ohms, exists between the PDL and the oral mucosa. Sunada conrmed Su-zuki’s ndings in humans and applied this principle to electronic apex determi-nation. Kobayashi and Suda developed the Root ZX apex locator [J. Morita] based on these ndings. Typical EALs like the Root ZX measure impedance val-ues that represent a ratio of resistances (Kobayashi and Suda) (Fig 8-4). Research indicates that these devices are not only accurate but also useful un-der many clinical conditions. Shabahang et al found that EALs accurately locat-ed the apical foramen 96% of the time. However, Ounsi and Naaman found that they were more useful to determine the major diameter than the minor diameter. Their accuracy does not differ when used in vital or necrotic cases (Dunlap et al), in the presence of apical root resorption (Goldberg et al), or in the presence of apical periodontitis (Saatchi et al). Lastly, their accuracy is not affected by the presence of solutions, including lidocaine, sodium hypochlorite, RC-Prep [Premier Dental], ethylenediaminetetraacetic acid (EDTA), hydrogen peroxide, and chlorhexidine (Jenkins et al). Their accuracy may be diminished when apical diameters are larger than 0.6 mm (Herrera et al). Just as their accuracy is similar to radiographs, no differences in postoperative pain were noted when WLs were measured with either method (Kara Tuncer and Gerek). Not only are EALs an accurate means to measure WL, they provide a safe means for WL determination in patients with pacemakers. Historically, EALs were considered unsafe based on work by Wooley et al. However, recent research has failed to demonstrate an effect of these units on pacemaker function or safety. An in vitro study by Garofalo et al showed no effect on pacemaker function when EALs were directly connected to the units. An in vivo study by Wilson et al further supported these results. Similarly, Idzahi et al found that these units are safe to use in patients with implantable cardiac debrillators (ICD). The same study, however, indicated that electrosurgical units might alter ICD function. Guide path maintenance and patencyWith WLs established, a glide path to the apex must be maintained. Some authors ad-vocate the maintenance of apical patency at the WL by passing small les through the cementodentinal junction (CDJ). Vera et al (2012a) found that maintaining apical patency decreased irrigant vapor lock in large canals by a signicant margin, thus increasing irrigant Fig 8-4 A Root ZX electronic apex locator. These units utilize impedance values to accurately mea-sure root canal lengths. Their accuracy is not dimin-ished by apical periodontitis, root resorption, or the presence of irrigants. 126Treatment of Endodontic Disease8Instrumentation Endodontic instrumentation serves to remove debris (Dalton et al), permit irrigant penetra-tion to the apex (Salzgeber and Brilliant), and prepare the canal for obturation (Schilder 1974). Several root canal instrumentation techniques have been described in the literature. These techniques include the step-down (Goerig et al), passive step-back (Torabinejad), anticurva-ture ling (Abou-Rass et al), balanced force (Roane et al 1985), and crown-down techniques (Morgan and Montgomery) (Fig 8-6). According to Wu and Wes-selink, all of these techniques leave residual debris behind to a similar degree. Consequently, technique selection should be based on operator experience and preference. In addition to the multitude of instrumentation techniques de-scribed, several types of instru-ments, including both hand and rotary instruments, are available to practitioners. Hand instru-ments are often fabricated out of stainless steel, whereas rotary efciency at the apex. In addition to an increase in irrigation efciency, Arias et al found less postoperative pain when patency was maintained in nonvital teeth. Silva et al, on the other hand, found no signicant differences in postoperative discomfort whether or not patency was maintained. Regardless of the effect of patency maintenance on irrigation efciency or postoperative discomfort, traversing the apical foramen with small les may have a detrimental effect on apical anatomy. Goldberg and Massone found that passing les through the periapex caused transportation of the apical foramen regardless of le size or instrument type. Ador-no et al demonstrated a signicant increase in the presence of apical cracks as a result of foraminal enlargement. Because of such demonstrable damage, one must carefully consid-er the practice of patency maintenance. Arguments both for and against the maintenance of apical patency are summarized in Fig 8-5. Fig 8-5 Positive and negative ndings associated with the maintenance of api-cal patency by passing instruments through the apical foramen.• Improves efciency of irrigation at the apex• May decrease post-operative pain• Causes transpor-tation of the apical foramen• Increases the num-ber of apical cracksPositivesNegativesFig 8-6 Commonly described instrumentation techniques and the authors to whom they are attributed.Step-downPassive step-backAnticurvature lingBalanced forceCrown-downGoerigTorabinejadAbou-RassRoaneMorgan and Montgomery 127Nonsurgical Root Canal TherapyInstrumentation of the apical portion of the canal is often described with respect to the master apical le (MAF). Salzgeber and Brilliant found that a minimum MAF size of a no. 30 K le allowed penetration of irrigants to the apex. Other authors, including Mickel et al, have suggested that the MAF size should reect the size of the apex. They found that by using a crown-down technique to assess apical size, followed by an increase in three le sizes to nal instrumentation, greater bacterial reduction was noted than if only one le size greater than the initial was selected. Similarly, Saini et al found that outcomes were signicantly improved when the MAF was three sizes larger than the initial apical size and that further enlargement did not provide any additional benet. Consequently, absolute master apical le size recommendations may be inappropriate. Instrumentation, though effective in shaping the root canal system and removing debris, produces a smear layer. Mader et al found that the smear layer consisted of two conuent components: the smeared layer on the surface of the canal wall and debris packed in den-tinal tubules. McComb et al found that all standard instrumentation techniques produced this layer. Controversy exists as to whether or not this layer needs to be removed prior to instruments are frequently constructed from nickel titanium (NiTi) alloys (Hargreaves et al). NiTi alloys cycle through several temperature-dependent crystalline structures, including the stiffer austenite phase, the intercrystalline R phase, and the more exible low-tempera-ture martensite phase (Shen et al 2013). Newer instruments are fabricated from controlled memory (CM) wire, a heat-treated NiTi substance in which the austenite nish temperature is higher than body temperature, thus keeping the instrument in the more exible mar-tensite and R phases (Shen et al 2013). This technology improves NiTi fatigue resistance over conventional instruments (Shen et al 2011). According to Dalton et al, both hand and rotary instruments reduce intracanal bacterial levels to a similar degree. However, Short et al found that rotary instruments remain better centered in the root canal system. With instruments and techniques selected, cleaning and shaping of the entire root canal system can commence. Instrumentation of the coronal portion of the canal, referred to as coronal aring, has several functions (Fig 8-7). It provides straight-line access to the apical portion of the canal (Schroeder et al), and allows the apical foramen to be reached more consistently when read with EALs (Ibarrola et al). Furthermore, Roland et al found that prearing decreases the incidence of rotary instrument separation. However, this pro-cess leads to a change in WL measurements; although, according to Schroeder et al, this change is clinically insignicant. Fig 8-7 Functions of coronal aring. Provide straight-line access to the apical portion of the canalAllow the apical fora-men to be reached more consistently with EALsDecrease the incidence of rotary instrument separation 128Treatment of Endodontic Disease8Sodium hypochlorite is the most commonly used endodontic irrigant, as it fullls many of Zehnder’s criteria. Its properties are summarized in Fig 8-9. Baumgartner and Mader found that sodium hypochlorite dissolves necrotic tissue and the organic component of the smear layer, while Rosenfeld et al found that it dissolves vital tissue. Sodium hypochlorite effectively eradicates endodontic pathogens, including planktonic bacteria (Haapasalo et al), those in established biolms (Del Carpio-Perochena et al), as well as bacteria that have penetrated into the dentinal tubules up to 0.3 mm (Wong and Cheung). root canal obturation. Those who advocate for its removal include Taylor et al, who found less coronal leakage with its removal, and Sen et al, who found that the smear layer blocks the disinfecting properties of both sodium hypochlorite and chlorhexidine. Those who rec-ommend leaving it intact include Madison and Krell, who found that the layer did not affect an apical seal, and Clark-Holke et al and Drake et al, who found more bacteria with the layer removed. Irrigation Endodontic instrumentation alone cannot render root canal systems free of debris. Ac-cording to Peters et al, endodontic instrumentation leaves 35% of canal walls untouched. Furthermore, the existence of isthmuses between canals and lateral canal anatomy has been well documented in the literature (Senia et al), and often, instruments do not reach these areas. Consequently, irrigation is necessary to ush the root canal system of debris and eradicate microbes. According to a review by Zehnder, the ideal irrigant possesses broad antimicrobial properties, is highly effective against anaerobic and facultative micro-organisms, dissolves both vital and necrotic tissue, inactivates lipopolysaccharide (LPS), and either prevents the formation of the smear layer during instrumentation or dissolves it once formed. Ideal irrigant properties are summarized in Fig 8-8. Broad antimicrobial propertiesEither prevents formation of the smear layer or dissolves it once formedInactivates LPSHighly effec-tive against anaerobic and facultative organismsDissolves both vital and necrotic tissueFig 8-8 Properties of the ideal endodontic irrigant. Though many irrigants possess one or several of these capabilities, no one irrigant available today fullls all criteria (Zehnder). 129Nonsurgical Root Canal TherapyMost AAE members report using sodium hypochlorite at concentrations of 5.25% or greater (Dutner et al). Several literature justications exist to support the use of this concen-tration. Hand et al found that 5.25% sodium hypochlorite was most effective at dissolving necrotic tissue, and Senia et al found it was the best concentration for removing vital tissue. Harrison et al found that this concentration was safe for clinical use and did not increase postoperative pain. Morgental et al found that 5.25% sodium hypochlorite was more effec-tive than either chlorhexidine or QMix irrigation solution [Dentsply]—a product containing chlorhexidine, EDTA, and surfactant—at eradicating Enterococcus faecalis. Despite reports on concentration effectiveness, it is clear that great variation exists in sodium hypochlo-rite concentrations obtained commercially, and less free chlorine is often available than is reported on the label (van der Waal et al). Consequently, practitioners must pay close attention to the products they purchase. Although sodium hypochlorite effectively disinfects the root canal system and dissolves tissue, it lacks the ability to dissolve the mineralized component of the smear layer. As a result, many practitioners use chelating solutions as part of their irrigation protocols. EDTA chelates calcium ions, effectively targeting dental hard tissue debris (Calt and Serper). Calt and Serper found that a 1-minute rinse with EDTA removed the smear layer in its entirety, although a 10-minute application resulted in excessive dentin erosion. Additionally, Dai et al found that QMix was as effective as 17% EDTA in removing the smear layer. Consequent-ly, practitioners now possess several choices in demineralization solutions. Caution must be exercised when both EDTA and sodium hypochlorite are used in the same procedure, as their combined use can result in excessive demineralization of tooth structure. Qian et al found that sodium hypochlorite, if used as a nal irrigant after EDTA, caused marked erosion of root canal dentin. Baumgartner and Mader found that when both solutions were alternated, excessive loss of intertubular dentin occurred. Furthermore, when solutions are combined, EDTA can reduce the efcacy of sodium hypochlorite. Clarkson et al found that the active chlorine content of sodium hypochlorite was reduced when mixed with EDTA. Consequently, practitioners must design their irrigation protocols carefully. • Dissolves necrotic tissue• Dissolves vital tissue• Removes the organic component of the smear layer• Kills planktonic bacteria• Kills bacteria in established biolms• Kills bacteria in dentinal tubulesSodium hypochloriteFig 8-9 Properties of sodium hypochlorite that make it an effective endodontic irrigant. 130Treatment of Endodontic Disease8In addition to sodium hypochlorite and EDTA, chlorhexidine gluconate (CHX), a biguanide, has gained popularity as an endodontic irrigant. Jeansonne and White recommended its use in cases of allergy to sodium hypochlorite or with open apices where sodium hypochlorite ex-trusion would pose a risk. They found it was as effective as 5.25% sodium hypochlorite in terms of its antibacterial activity. Cook et al found that a 10-minute CHX soak was the most effective means to eliminate E faecalis from the root canal system. CHX also possesses the property of substantivity; it binds to dentin, allowing its antibacterial activity to persist for as many as 48 days after exposure (Baca et al). Despite these overwhelmingly positive ndings, CHX has several drawbacks. First, it lacks the ability to dissolve organic substances, namely vital and ne-crotic tissue (Okino et al). Second, as Basrani et al found, it reacts with sodium hypochlorite to form a red-brown, carcinogenic precipitate called parachloroaniline (Fig 8-10). This precipitate has the ability to occlude dentinal tubules (Bui et al). Recent research by Barbin et al suggested that this precipitate may be present in solutions of CHX alone and with its use in combination with calcium hydroxide. Consequently, CHX should be used cautiously. CHX (liquid)Parachloroaniline (solid)Sodium hypochlorite (liquid)Fig 8-10 The chemical reaction between CHX and sodium hypochlorite solutions to produce the red-brown precipitate parachloroaniline (Basrani et al).Adjunctive irrigation techniquesJust as several irrigant solutions are available to practitioners, so are adjunctive irrigation techniques, including passive ultrasonic activation, sonic activation, photodynamic thera-py, and the EndoVac [Kerr] irrigation system (Fig 8-11). At this time, 45% of AAE members report using adjunctive irrigation techniques (Dutner et al). All techniques appear to offer improvements in disinfection, debridement, or both. The EndoVac system and photodynamic therapy offer improvements in debridement or bacterial reduction, but not both. According to Nielsen and Baumgartner, the EndoVac system offers signicantly better debridement than needle irrigation at a level 1 mm from the apex, most likely because it improves delivery of the irrigant to the apex (Munoz and Camacho-Cuadra). It may also improve sealer penetration at the apex (Kara Tuncer and Unal). Despite these improvements, Beus et al found that the EndoVac offers no improve-ment in bacterial reduction. Photodynamic therapy, according to Chrepa et al, is effective at reducing microbial loads; however, limited clinical studies exist. 131Nonsurgical Root Canal TherapyPassive ultrasonic irrigation (PUI) improves both debridement and disinfection. Further-more, according to Jensen et al, sonic activation offers debridement equivalent to PUI. By creating acoustic streaming patterns (Ahmad et al), PUI improves the cleanliness of both the main canal and isthmuses (Gutarts et al). It is more effective than syringe irrigation in removing debris from depressions in the canal space (Malki et al). PUI is also as effective as a nal rinse with CHX in eliminating bacteria (Beus et al). Grundling et al, however, assert that bacterial elimination during PUI is a function of the irrigant rather than the activation. Despite the improvements PUI has over standard needle irrigation, Liang et al found no signicant differences in periapical healing when this technique was employed. Single-visit therapy versus multiple-visit therapyEndodontic therapy can be completed in a single visit or over the course of multiple visits. Arguments both for and against sin-gle-visit endodontic therapy often focus on one of three factors (Fig 8-12): the eradication of bacteria, the effect on postoperative pain, and the effect on prognosis. A thorough re-view of the literature reveals that both single- and multiple-visit treatment can be supported based on those three subjects. Consequently, treatment either in a single visit or in multiple visits is justiable, and the choice lies at the discretion of the practitioner. Vela et al found that though many patients would prefer sin-gle-visit therapy, most would follow their den-tist’s recommendation for two-visit therapy if an improved outcome was expected. While several reports indicate that the root canal system cannot be reliably cleaned of Fig 8-11 Commonly researched adjunctive irrigation techniques. These offer improve-ments in debridement, disinfection, or both. Passive ultrasonic activationPhotodynamic therapySonic activationEndoVac irrigation systemFig 8-12 Three factors used to justify single- visit endodontic therapy versus multiple- visit therapy. Positions supporting either treatment can be defended based on any of these considerations.Inuence on prognosisEffect on post-treatment painCapacity to disinfect 132Treatment of Endodontic Disease8bacteria in a single visit without use of an interappointment, intracanal medicament, other research found that disinfection was not improved with medicaments. Sjogren et al (1991) found that thorough disinfection of the root canal system required 7 days of treatment with calcium hydroxide (CH), and bacteria were not sufciently eliminated after 10 minutes or 24 hours of exposure to the medicament. Law and Messer found that interappointment treatment with CH increased the number of root canals with undetectable levels of bac-teria. Xavier et al interestingly found no difference in bacterial reduction in single versus multiple visits but found that two-visit treatment with CH eliminated more LPS than root canal therapy completed in a single visit. On the other hand, several studies found that two-visit therapy does not increase bacterial disinfection. Peters and Wesselink found that, in two-visit therapy, bacterial regrowth was not prevented by interappointment CH, and no further disinfection was evident. Vera et al (2012b) found that, after two-visit treatment with CH dressing, bacteria were still evident in the isthmuses and other canal ramications but not within the main canal or dentinal tubules. Pain outcomes are also cited as reasons both for and against single-visit treatment. Like those for bacterial reduction, literature justications exist to support either position. Soltanoff and Figini et al found that patients experienced more pain following single-visit treatment. Conversely, both Roane et al (1983) and Eleazer and Eleazer found more pain and more frequent are-ups in multiple-visit treatment. Between these two extremes are authors, namely Pekruhn as well as Walton and Fouad, who found no differences in pain experienced by either group. The last area often discussed in reference to single- and multiple-visit therapy is the effect on prognosis. Like bacterial reduction and pain, evidence for and against single-visit treatment based on prognosis is present in the literature. Trope et al found that two-visit therapy improved outcomes in necrotic cases. Similarly, Peters and Wesselink found a ten-dency for increased healing when two-visit endodontic therapy was performed, though re-sults were not statistically signicant. However, several studies rebuff these ndings. Stud-ies by Penesis et al, Molander et al, and Paredes-Vieyra and Enriquez and a meta-analysis by Su et al found no difference in outcomes between teeth treated in a single visit or over multiple visits. Intracanal medicamentsIf the decision to perform multiple-visit root canal therapy is made, the use of an intracanal medicament is recommended. The purpose of the medicament is to aid in disinfection and prevent recolonization of the root canal space with bacteria. Bystrom and Sundqvist demonstrated that, without the use of an intracanal medicament, canals rendered bacteria free during instrumentation exhibited culture reversals. Several medications are available to practitioners including CH, CHX gel, and antibiotic pastes. For further information re-garding intracanal antibiotic pastes, please refer to the section in this chapter on regener-ative endodontics. CH has a basic pH between 11 and 12 and diffuses into dentinal tubules, causing an in-crease in the pH of outer root dentin after 2 to 3 weeks (Nerwich et al). These effects do not extend into cementum or the adjacent PDL space, indicating that the cementum may act as a buffer (Tronstad et al). The most effective means of delivering CH into the root canal space is the lentulo spiral, followed by injection and K les (Sigurdsson et al). CH eliminates 133Nonsurgical Root Canal Therapythe majority of bacterial species in the root canal system, though some anaerobic species (Sjogren et al 1991) and E faecalis may be resistant to its effects (Siren et al). In addition to its antibacterial effects, CH reduces the cytotoxic response to LPS by destroying its lipid A moiety (Safavi and Nichols). CH may also dissolve tissue remaining in the root canal space after instrumentation (Hasselgren et al). Furthermore, it is the favored intracanal medica-ment for regenerative endodontic therapy as it is less cytotoxic than antibiotic pastes or CHX against apical papilla stem cells (Ruparel et al). Interestingly, the combination of CH and omeprazole resulted in superior repair of rat periapical lesions when compared with conventional CH (Wagner et al).Despite its positive effects, care must be exercised with CH as it may negatively impact the physical properties of both teeth and root canal lling materials. Blomlof et al demon-strated that long-term applications could cause PDL necrosis. Additionally, Andreasen et al found that long-term CH decreased dentinal fracture resistance. CH can also negatively impact surrounding anatomical structures. Care should be taken to prevent its overexten-sion into tissue spaces as it has been associated with devastating tissue necrosis (Lindgren et al) and paresthesia (Ahlgren et al). Lastly, CH may inuence obturation because it inhibits setting of eugenol-based sealers (Margelos et al). Remaining CH can affect the penetration of sealers into dentinal tubules and increase apical leakage (Kim and Kim). Consequently, its thorough removal is imperative prior to obturation. Passive ultrasonic irrigation (Capar et al) or rotary instrumentation (Kenee et al) are more effective than syringe irrigation at removing CH from the canal system. Peracetic acid was found to remove more CH than sodium hypochlorite or EDTA (Sagsen et al). CHX gel is often suggested as an alternative to CH. Like CH, it possesses broad anti-bacterial abilities. Wang et al found that 2% CHX gel is an effective root canal disinfectant. It is effective against gram-positive and gram-negative bacteria, both aerobic and an-aerobic species, and fungi (Waltimo et al). Furthermore, it exhibited greater antibacterial activity against E faecalis than CH (Buck et al). Like CH, CHX also reduces intracanal LPS (Oliveira et al). Lastly, CHX alters periapical healing responses. Not only does its application between appointments prevent the increase of pro-inammatory and immunoregulatory cytokines (Tavares et al), but more favorable healing of periapical lesions was noted with CHX application than with CH (Leonardo et al). Properties of CH and CHX are summarized in Fig 8-13. CH CHX• Demonstrates broad microbial properties• Eradicates LPS• Dissolves tissue• Provides favorable cytotoxicity prole toward apical papilla stem cells• Demonstrates broad antimicro-bial properties• Eradicates LPS• Reduces pro-inammatory cyto-kine expression in the periapex• Improved periapical healing over CHFig 8-13 Properties associated with CH and CHX intracanal medicaments that make them useful for endodontic therapy. 134Treatment of Endodontic Disease8Filling techniques with this material include lateral condensation and vertical condensa-tion. Neither leakage nor outcomes appear to be inuenced by lling technique. Jacobson et al found that, though teeth obturated by lateral condensation leaked microbes faster than those lled by vertical condensation, no differences in the numbers of teeth that leaked were noted. No differences were noted in voids between the two techniques (Read-er et al). Lastly, no differences in outcomes were noted between teeth treated with either technique (Peng et al).Resilon [Resilon Research] offers an alternative to GP llings; it is a polyester core material used with a resin-based sealer (Orstavik). Though previous research suggested that Resilon offered superior lls to GP (Teixeira et al), other work suggested that lls offer no improve-ments over GP in terms of leakage (Biggs et al) or movement into three-dimensional anatomy (Karr et al). Although Resilon was thought to create a “mono block” lling material whereby the sealer bonded both to dentin and to the lling material (Teixeira et al), research does not support these claims (Gesi et al). Carrier-based systems provide an alternative to GP, though the lling quality they provide may be inferior to other techniques. These are marketed as offering signicant time savings and ease over other obturation systems. However, research shows that the carrier-based lling materials result in lls that leak signicantly more than laterally or vertically condensed GP (Baumgardner et al).Obturation Following cleaning and shaping of the root canal system, placement of a three- dimensionally adapted lling is indicated (Schilder 1967). Several materials and techniques are available to accomplish this goal. Traditional root canal lling material is composed of gutta-percha (GP), described in Fig 8-14. GP is closely related to rubber and is a naturally occurring polymer of isoprene (Goodman et al 1974). GP cones are composed of zinc oxide (65%), GP (20%), and other materials including waxes, resins, and metals (Goodman et al 1974). GP is in its beta crystalline state when in cone form and undergoes a change to the alpha crystalline state when heated between 42ºC and 49ºC (Goodman et al 1981). GP designed for thermoplastic applications shrinks quickly and extensively upon cooling and differs signicantly between brands (Lottanti et al). As GP is chemically close to rubber, care should be used in patients with a severe type I allergy to latex (Costa et al, Orstavik). • Trans-isoprene, chemically related to natural rubber latex• Cones are composed of 65% zinc oxide, 20% GP, and 15% waxes, resins, and metals• Commercially available in the beta crystalline phase• Changes to alpha crystalline phase on heatingGPFig 8-14 Common properties of GP obturation materials. 135Nonsurgical Root Canal TherapyNo matter which technique is used to obturate the root canal system, sealer is an essential component (Marshall and Massler). Several sealers are commercially available, including euge-nol-based products, resin/epoxy–based products, glass-ionomer–based products, silicone-based products, and CH-based products. Recently, sealers-based on mineral trioxide aggregate (MTA) have become available (Vitti et al). Sealers are often compared in terms of biocompatibility, ease of use, antibacterial activity, adherence to dentin, and other properties (Orstavik). It behooves the practitioner to select an appropriate product based on these properties and one’s personal preferences. No matter which sealer is selected, placement can be completed with K les, lentulo spirals, or GP cones with no effect on ll quality (Wiemann and Wilcox). Instrumentation and obturation should terminate at the CDJ (Ricucci), as overinstrume-nation and overlling cause periapical inammation (Seltzer et al). Obturation materials, in-cluding particulate GP, have been associated with robust inammatory responses (Sjogren et al 1995). Though Augsburger and Peters found that sealers expressed into the periapical tissues resorb radiographically over time, care should be taken to avoid doing so because these materials have been associated with chronic inammation (Seltzer et al), sinus infec-tion with Aspergillus (Giardino et al), and paresthesia (Gonzalez-Martin et al).Temporary restorationsFollowing completion of root canal therapy, and prior to placement of the denitive coronal restoration, temporary restorative materials are used to seal the coronal access, thus pre-venting contamination of the root canal lling with oral microbes (Swanson and Madison). Several temporary lling materials are commercially available, including but not limited to Cavit [3M ESPE], Intermediate Restorative Material (IRM) [Dentsply], and glass-ionomer ce-ments. In a study by Turner et al, all of the aforementioned materials adequately prevented microleakage. For adequate prevention of leakage with Cavit, Webber et al found that a 3.5-mm-thick seal was necessary. Lamers et al showed that Cavit leaked after 42 days, sup-porting its use only in the short term. Barthel et al showed that both Cavit and IRM leaked signicantly more than glass ionomers. Consequently, glass ionomers may be the materials of choice for temporary restorations. Eugenol is found in several temporary restorations and in root canal cements. This clove oil derivative exhibits several biologic activities worth mentioning (Fig 8-15). Eugenol alters neurotransmission (Kozam) via increased potassium permeability and decreased sodium inux in nerves, thus decreasing the rate at which action potentials re (Trowbridge et al). Furthermore, eugenol blocks the expression of neuropeptides associated with inamma-tion (Trowbridge). Lastly, it decreases the vasoconstriction response to epinephrine (Mjor). • Alters neurotransmission by increasing potassium permeability and decreasing sodium inux • Blocks neuropeptide expression• Decreases the vascular response to epinephrineEugenolFig 8-15 Commonly reported properties of eugenol. 136Treatment of Endodontic Disease8Nonsurgical RetreatmentNonsurgical retreatment is indicated when symptoms or radiographic pathology are evi-dent in endodontically treated teeth. Factors associated with persistent or recurrent apical periodontitis include coronal leakage (Ricucci and Siqueira), intraradicular infection (Vieira et al), extraradicular infection, untreated canal anatomy, fractures, foreign body reactions, and true cystic lesions (Nair). With proper case selection, the prognosis of nonsurgical retreatment is favorable (Salehrabi and Rotstein). Despite the often-favorable outcomes, many general dentists prefer to pursue extraction of teeth with recurrent apical periodon-titis in favor of implant placement (Azarpazhooh et al). Consequently, specialists must edu-cate their referral base regarding both treatment possibilities and their prognosis. Post removalPosts are often the rst obstacles encountered in a retreatment case. According to John-son et al, 16 minutes of ultrasonic vibration is an effective means to remove metal posts. In addition to their efcacy, ultrasonics are safe for use, even in patients with pacemaker units (Gomez et al). Care must be taken, though because ultrasonics produce signicant amounts of heat and are thus capable of causing bony damage. Dominici et al found that temperature increases approaching 10ºC occurred in as little as 15 seconds without irriga-tion. Thankfully, Huttula et al found that the use of an irrigant maintained the temperature well below that which could cause bony damage. The removal of ber posts can be accom-plished most effectively with either burs or ultrasonic vibration, though these methods are slower than commercially available kits (Lindemann et al).Gutta-percha removal The ability of retreatment techniques to remove GP llings depends not only on the com-position of the sealer (Neelakantan et al, Hess et al) but also the type of instruments used (Xu et al). Retreatment of GP root canal lings often employs the use of solvents. Kaplowitz found that of ve tested solvents, chloroform was the only solvent able to completely dissolve the GP. Not only is chloroform safe for both patients (Chutich et al) and providers (McDonald and Vire) if used properly, it also aids in disinfection of the root canal space (Edgar et al). Ferreira et al found that the combination of chloroform and either rotary or hand instrumentation produced similarly clean canals; however, rotary methods were sig-nicantly faster. Care must be taken no matter which method is chosen as both can cause defects in canal walls (Shemesh et al).“Russian Red” removalA combination of formaldehyde and resorcinol used in conjunction with a sodium hydroxide catalyst produces the paste-like lling material often referred to as “Russian Red.” These components solidify following their introduction into the root canal space with an appropri-ate instrument. Retreatment of Russian Red is often difcult, as the llings produced by this material range in consistency from sap-like to rock hard (Schwandt and Gound). Unlike GP llings, solvents do not affect Russian Red endodontic pastes. Vranas et al found that both 137Nonsurgical RetreatmentSilver pointsSilver points were historically used to obturate the root canal system. The AAE recommends against the further use of this material due to its inferiority to modern techniques. Not only do silver points represent less effective obturation materials, but Seltzer et al found that they corrode in the presence of tissue uid, producing highly toxic corrosion byproducts. The AAE holds that, while prophylactic revision of silver points is not indicated, retreatment is recom-mended in the presence of pathology or when their presence complicates proper restorative care. Retreatment techniques effective at removing these materials include ultrasonic removal of surrounding sealer, bypassing with instruments, or the use of a Masserann technique involv-ing trephination around the coronal portion of the ll followed by insertion of a tube to extract the piece (Krell et al). A silver point retreatment case is illustrated in Fig 8-17. chloroform and Endosolv R [Septodont] had no effect on the material, while both sodium hypochlorite and sodium chloride had only marginal efcacy. Ultrasonics may provide an effective means for removal of the paste (Krell and Neo), though if the ll is solidied to the apex, one may not be able to gain patency. Another technique involves bypassing with les, though as with ultrasonics, success is dependent on lling consistency (Schwandt and Gound). A retreatment case of Russian Red is illustrated in Fig 8-16. Fig 8-16 Preoperative (a) and postoperative (b) radiographs of a retreatment procedure on a tooth previously treated with the Russian Red technique. Judi-cious use of an ultrasonic instrument allowed the clinician to bypass the hard-ened material, and small les were used to reach the apex.Fig 8-17 Preoperative (a) and postoperative (b) radiographs of a retreatment procedure on a tooth initially obturated with silver points. Bypassing and the Masserann technique were implemented to remove the points. aabb 138Treatment of Endodontic Disease8Carrier-based system removalCarrier-based obturation techniques have become more widely used, necessitating the development of effective retreatment strategies for these materials. Both metal and plastic carriers are impervious to chloroform (Wilcox). Consequently, an effective technique for their retreatment involves the combination of chloroform to soften the surrounding GP and hand les to remove the carrier (Bertrand et al). Rotary instruments have also been advocated for the removal of these llings (Royzenblat and Goodell), though instrument speed must be kept at manufacturers’ recommended levels to decrease the incidence of instrument separation. Lastly, heated instruments, like the System B endodontic ll device [Kerr], may be effective for removal of carrier-based llings. According to Wolcott et al, temperature settings must be maintained below 300ºC to avoid melting the plastic carrier. Retreatment of a carrier-based root canal lling is illustrated in Fig 8-18.Fig 8-18 Preoperative (a) and postoperative (b) radiographs of a retreat-ment procedure on a tooth initially obturated with a carrier-based material.a bSurgical EndodonticsSurgical endodontic therapy seeks to resolve periapical pathology when orthograde end-odontic treatment is not feasible (Iqbal et al). Tools and techniques have evolved signi-cantly since surgical therapy was developed, and with these advancements have come improved outcomes (Setzer et al). Modern advances in surgical techniques include mag-nication with loupes or microscopes (Von Arx et al 2010), ultrasonic retropreparations (de Lange et al), and improved lling materials (Song and Kim). With proper case selection and the use of modern techniques, surgical endodontics provides patients with a predictable means of eradicating periapical pathology (Tsesis et al 2013). Lastly, as nancial concerns may play a role in patients’ pursuit of dental treatment, it should be noted that surgery is often more cost effective than nonsurgical retreatment (Kim and Solomon). This section covers basic surgical literature. A more complete surgical reference can be found in Kim et al’s Color Atlas of Microsurgery in Endodontics. 139Surgical EndodonticsHemostasisEffective hemostasis is essential during endodontic surgery to maintain visibility in the op-erative eld (Gutmann). Furthermore, hemostatic measures curb the amount of blood loss during surgical intervention. According to Selim et al, an average of 9.5 mL of blood is lost during surgery. Several measures are available to the clinician to curb intraoperative blood loss. The rst measure involves a thorough review of a patient’s medical history including as-sessment of medication and supplement use (Witherspoon and Gutmann). Doing so allows the clinician to anticipate difculties with hemostasis prior to surgical intervention and devel-op an appropriate plan. In certain cases following consultation with the prescribing physician, alterations in medication use may be made preoperatively to minimize bleeding risk. During surgery, clinicians have several hemostatic measures at their disposal. Historically, bone wax was employed for hemostasis, though it has fallen out of favor because it caus-es a robust inammatory response (Ibarrola et al). Epinephrine is an effective hemostat-ic agent via its interaction with blood vessel alpha receptors, producing vasoconstriction (Gutmann). Local anesthetics containing a 1:50,000, rather than the more commonly used 1:100,000, concentration of epinephrine reduce blood loss by half and offer better visibili-ty, reduced surgical time, and improved postoperative hemostasis (Buckley et al). Racellet hemostatic cotton pellets [Pascal], containing 0.55 mg of racemic epinephrine per pellet, also promote surgical hemostasis without risking cardiovascular effects (Vickers et al). Ferric sulfate also produces excellent hemostasis in the surgical eld (Vickers et al), though it re-quires curettage prior to wound closure to prevent the formation of a foreign body reaction (Jeansonne et al). Other local hemostatic measures include collagen-based agents like Col-laCote [Zimmer], gelatin-based products like Gelfoam [Pzer], and cellulose-based prod-ucts like Surgicel [Ethicon] (Witherspoon and Gutmann). Lastly, calcium sulfate was recently investigated for use in endodontic surgery and was found to provide effective hemostasis (Scarano et al). Hemostatic measures for endodontic surgery are summarized in Fig 8-19. Fig 8-19 Common hemostatic agents available during endodontic surgery.Racemic epinephrine pellets (0.55 mg epinephrine per pellet)Anesthetics containing a 1:50,000 concentration of epinephrineFerric sulfateCollagen-based agentsCellulose-based agentsGelatin-based agentsCalcium sulfate 140Treatment of Endodontic Disease8Horizontal incisions are connected to vertical incisions to create the soft tissue ap. The use of a single vertical releasing incision creates a triangular ap, whereas two vertical incisions create a rectangular or trapezoidal ap (Velvart and Peters). When creating a rect-angular ap, a length-to-width ratio of 2:1 is recommended (Velvart and Peters). The osteotomy exposes the root apex for inspection and can be created with the use of burs under coolant spray (Kim et al). The osteotomy should be large enough to permit manipulation of ultrasonic tips. Its size, however, should be limited, as smaller osteotomy preparations are associated with more favorable outcomes (Barone et al). Exposure of the surgical siteSoft tissue mobilization permits access to the periapical tissues, and both horizontal and vertical incisions are used during this process. Several incision types are available for prac-titioners and must be carefully selected; the choice of incision technique may affect the patient’s postoperative quality of life (Del Fabbro et al). Commonly used types of hori-zontal incisions for endodontic surgical applications include the intrasulcular, submarginal, semilunar, and papilla-based incisions. Intrasulcular incisions extend through the gingival sulcus and expose the entirety of the root structure for inspection (Velvart and Peters). They are associated with more postoperative recession and scarring than other incision types (Kramper et al). Submarginal incisions, also known as the Oschenbein-Luebke technique, require a minimum of 2 mm of attached gingiva and do not expose the cervical third of the root (Velvart and Peters). Scalloping of this type of incision is often recommended to pro-vide landmarks during ap closure (Vreeland and Tidwell). The scalloped submarginal inci-sions are associated with better epithelial closure than submarginal or semilunar incisions but do pose a risk for scar formation (Kramper et al). Semilunar aps incise into the alveolar mucosa and expose a minimal amount of root structure for visualization; consequently, they are infrequently used in endodontic surgery (Velvart and Peters). Lastly, the papilla-based incision represents a modication of the intrasulcular technique and permits visibility of the entire root surface, while mitigating the risk for recession by preserving the interdental papillae (Velvart et al). Horizontal incision techniques are summarized in Fig 8-20. IntrasulcularSubmarginalSemilunarPapilla-basedFig 8-20 Commonly used horizontal incision types for surgical endodontics. 141Surgical EndodonticsResection and retropreparationApical surgery involves both resection of the root apex and preparation into the root canal system and should be completed with the use of a coolant to avoid overheating of the bone (Nicoll and Peters). Resection of the root apex can be quite simply accomplished by burs in a high-speed handpiece (Kim et al). Block et al advocated 3 mm of apical resec-tion to remove the majority of apical deltas. However, Weller et al reported that a 4-mm resection of the mesiobuccal root of the maxillary rst molar may be necessary to expose intercanal isthmuses. Historically, resection involved beveling to improve visualization. However, recent trends shy away from bevels because they are associated with leakage (Gilheany et al). The number of dentinal tubules increases from the CDJ to the canal wall, and consequently retrollings must extend to the most coronal aspect of the bevel, lest potentially contaminated open tubules be exposed (Tidmarsh and Arrowsmith). Following resection of the root surface, it should be inspected for fractures, additional anatomy, and other ndings. Methylene blue dye is often utilized during the inspection process. Methylene blue dye is a biocompatible reducing agent, notable for its use in the treatment of methemoglobinemia. In endodontics, it outlines root anatomy, delineates dentin from bone, stains isthmuses, and can aid in visualization of fractures (Cambruzzi et al). On resection and inspection of the root surface, retropreparation into the canal system can commence. Matisson et al recommended a 3-mm depth for all retropreparations, and historically, burs were utilized for this purpose (Wuchenich et al). Burs in high-speed hand-pieces have largely been replaced by surgical ultrasonic tips. Several types of surgical ul-trasonic tips are available, including diamond-coated tips and those with microprojections; both are equally effective for surgical applications (Liu et al). According to Wuchenich et al, apical preparations with ultrasonic tips followed the direction of the root canal system, had parallel walls, and had a minimum depth of 2.5 mm. Bur preparations, on the other hand, had an average depth of 1 mm and were covered in a smear layer. Additionally, according to Rainwater et al, ultrasonics are no more likely to crack root structure than burs. Overall, ultrasonic retropreparations are associated with more favorable outcomes (de Lange et al). Just as ultrasonics effectively clean the root canal space, they are useful for cleaning the isthmuses often located between canals (Engel and Steiman).RetrollingPractitioners have a variety of retroll choices available to them, including amalgam, Super EBA [Bosworth], MTA, and the more recently introduced bioactive cements. Amalgam rep-resents the historical retroll of choice. However, amalgam is associated with more leak-age (Torabinejad et al 1995), poorer biocompatibility, more inammation (Baek et al 2010, 2005), and poorer outcomes (Setzer et al) than newer materials. Super EBA represents an improvement over amalgam in terms of both sealing capabilities (Oynick and Oynick) and toxicity (Keiser et al). Furthermore, outcomes with Super EBA are as favorable as those with newer lling materials including MTA (Song and Kim).MTA represents the current material of choice for many practitioners. It contains tricalci-um silicate, dicalcium silicate, tricalcium aluminate, bismuth oxide, and calcium dihydrate. The grey formulation additionally contains tetracalcium aluminoferrite (Camilleri et al). Upon setting, MTA forms calcium silicate hydrate and calcium hydroxide (Camilleri et al). MTA http://dentalebooks.com 142Treatment of Endodontic Disease8While the majority of endodontic surgeries involve retropreparation, several authors con-tend that this practice is unnecessary for both MTA apical plugs and GP llings. Andelin et al found that resection of set MTA does not diminish its sealing abilities. Harrison and Todd found that the resection of root ends with well-condensed GP does not adversely affect the seal, though the same is not true of silver point llings. Kaplan et al advocated that GP llings should be burnished after resection. Minnich et al suggested that even burnishing of well-sealed llings is unnecessary, though poorly condensed restorations may benet from burnishing. SuturingSutures immobilize the surgical ap and promote healing by primary intention (Harrison). Flaps should be reapproximated without tension to avoid impairment of ap circulation. Monolament synthetic sutures are recommended for this purpose, as they are less trau-matic, discourage inammation, and promote less bacterial adhesion than multilament sutures (Velvart and Peters). Smaller suture gauges, particularly the 6-0 and 8-0 sutures, are recommended to avoid tissue necrosis and minimize scarring. The suture technique selected, either simple-interrupted or continuous, should be appropriate for the clinical situation. Sutures should be removed 48 to 96 hours following surgery (Velvart and Peters).provides a marked improvement over older materials. It provides a better apical seal than amalgam, IRM, or Super EBA (Fischer et al), even in the presence of blood (Torabinejad et al 1994). Additionally, MTA promotes cementum and bone coverage, unlike amalgam or Super EBA (Baek et al 2005). Despite its many improvements, MTA possesses several drawbacks, including difcult handling and long setting time (Parirokh and Torabinejad). Newer iterations of MTA promise to address these undesirable properties.Recently, several bioactive materials have become available to practitioners. They rep-resent an improvement over MTA in terms of handling ease (Damas et al). These bioactive products are composed of calcium silicate and calcium phosphate (Damas et al). They are similar to MTA in terms of both in vitro (Damas et al) and in vivo biocompatibility (Ma et al). Furthermore, they create a mechanical bond to dentin, theoretically providing an excellent seal (Damas et al). Retroling materials are compared in Table 8-1. Table 8-1 Comparison of retroll materialsMaterial Biocompatible Seals well Ease of useAmalgam No No YesSuper EBA Moderate Yes Ye sMTA Yes Ye s NoBioactive cements Yes Unknown Yeshttp://dentalebooks.com 143Surgical EndodonticsBone grafts are often used with membranes and are available in both resorbable and nonresorbable forms (Bashutski and Wang). The concomitant use of both products is often referred to as guided tissue regeneration, a procedure that facilitates tissue regeneration to its original form (Caffesse and Quinones). This procedure is often used in periodontal surgery and is effective in the treatment of two- and three-wall intrabony defects and Class II furcation invasions (Caffesse and Quinones). For the majority of apical surgical proce-dures with loss of only one cortical plate, the use of membranes or grafts provides no advantages over traditional surgical techniques (Garrett et al). However, it may improve outcomes for treatment of through-and-through lesions (Lin et al 2010), large periapical defects (Tsesis et al 2011), or apicomarginal defects (Douthitt et al). For these indications, resorbable membranes are favored over nonresorbable membranes, and bone grafts may not be necessary except to hold the membrane in place (Tsesis et al 2011). Grafts and membranesBone graft materials and membranes are available for practitioners who wish to implement them during surgical intervention. Grafts fall under several broad categories, including osteogenic, osteoinductive, and osteoconductive grafts (Bashutski and Wang). Osteogenic grafts contain cells capable of depositing bony matricies. Osteoinductive grafts release mediators that signal the host to induce new bone formation. Lastly, osteoconductive grafts serve as scaffolds on which bone can grow. Grafts can be further categorized by source, including autogenous grafts, allografts, xenografts, and alloplasts (Bashutski and Wang). Autogenous grafts are derived from the host, allografts from a genetically dissimi-lar member of the same species, and xenografts from another species altogether. On the other hand, alloplasts are inert materials that serve as a scaffold for new bone but are not derived from biologic donors. Graft types are described in Fig 8-21. Osteogenic: Intrinsic capabilities for bone regenerationAutografts: Derived from the hostOsteoinductive: Can induce surrounding tissues to deposit boneAllografts: Derived from a genetically dissimilar member of the same speciesOsteoconductive: A scaffold upon which host bone cells can growXenografts: Derived from another speciesAlloplasts: Inert, nondonor materialGraft activity Graft sourceFig 8-21 Two means by which grafts can be categorized (Bashutski and Wang).http://dentalebooks.com 144Treatment of Endodontic Disease8Postoperative managementDiscomfort following surgery is often of short duration, with its maximum intensity in the early postoperative period (Chong and Pitt Ford), and is correlated with preoperative pain (Tsesis et al 2003). A long-acting postoperative anesthetic, such as bupivacaine, can mark-edly reduce postoperative discomfort in the initial period (Hargreaves and Keiser). Ad-ditionally, for a large number of patients, nonprescription analgesics are adequate and effective for management of postoperative pain (Chong and Pitt Ford). Antibiotics are not believed effective in managing postoperative discomfort. To aid in soft tissue healing after surgical procedures, Kim et al recommended the use of both pre- and postoperative chlorhexidine rinses to reduce soft tissue inammation. Shahan et al advised avoidance of chlorhexidine for 48 hours immediately postoperatively as it may reduce broblastic attachment to root surfaces and negatively affect tensile wound strength. Surgical complication managementA common complication encountered in apical surgery on maxillary posterior teeth is a perforation of the maxillary sinus (Rud and Rud) because of the close proximity of the maxillary posterior teeth to the sinus (Von Arx et al 2014). Thankfully, data indicate that these areas tend to self-repair, regardless of size, with a limited bony covering and a -brous scar (Tataryn et al). Furthermore, the use of resorbable membranes does not appear to improve osseous repair (Tataryn et al). Postoperatively, the use of “sinus precautions,” including avoidance of nose blowing and other activities involving forceful air production, as well as the prescription of a decongestant, is recommended whenever a sinus exposure is observed or suspected (Lin et al 1985). The prophylactic prescription of antibiotics is controversial. While Kim et al recommends this practice, Lin et al (1985), Rud and Rud, and Walton disagree.The mandibular posterior teeth lie in close proximity to the inferior alveolar nerve canal space (Denio et al). Several strategies are available to practitioners to aid in avoiding this structure, including preoperative CBCT to assess for of proximity (Kovisto et al), careful vertical incision placement, and grooving the bone to stabilize retractor placement (Moi-seiwitsch). That being said, sensory disturbance of a variable duration in the lower lip is evident in approximately 20% of all patients following mandibular molar surgery (Wesson and Gale). Thankfully, only 1% of patients retain a permanent decit. Surgical healingAndreason and Rud characterized healing after surgical intervention into three main types: healing with either reformation of the PDL or ankylosis and little inammation, healing with a brous scar, or moderate to severe inammation without the presence of scar tissue. Radiographic ndings associated with scar tissue formation include reduction in size of the apical radiolucency, formation of an irregular outline, and angular extension into the PDL space (Andreason and Rud). Regardless of outcome, healing progresses through several stages, including clotting and inammation, epithelial healing, connective tissue healing, maturation, and remodeling (Harrison). http://dentalebooks.com 145Surgical EndodonticsHarrison and Jurosky (1991a) described the common histologic ndings throughout these stages (Fig 8-22). Twenty-four hours postoperatively, they noted a thin epithelial seal, evi-dence of blood clotting, and a predominantly polymorphonucleocyte (PMN) inltrate. Fur-thermore, necrosis of the periostum was evident (Harrison and Jurosky 1991b). Forty-eight hours postoperatively, Harrison and Jurosky (1991a) observed a multilayered epithelial seal, early type III collagen production, and macrophages replacing PMNs as the dominant in-ammatory cell. Seventy-two hours postoperatively, collagen production continued (Harrison and Jurosky 1991a). Four days postoperatively, the clot was replaced by granulation tissue, type I collagen production began (Harrison and Jurosky 1991a), and osteocyte proliferation from the endosteum was noted (Harrison and Jurosky 1991b). Two weeks postoperatively, woven bony trabeculae occupied 80% of the wounded area, and new periosteum was evi-dent (Harrison and Jurosky 1991b). Furthermore, normal sulcular epithelium was noted at this time (Harrison and Jurosky 1991a). Twenty-eight days postoperatively, the bony wound was populated by maturing bony trabeculae (Harrison and Jurosky 1991b). Unconventional surgical approachesWhile the majority of practicing endodontists regularly perform apical microsurgery, two often-unmentioned surgical procedures within the scope of the specialty include intention-al replantation and autotransplantation. Intentional replanatation was dened by Gross-man as “removal of a tooth and its almost immediate replacement, with the object of obturating the canals apically while the tooth is out of the socket.” While this procedure is not indicated when conventional endodontic therapy or apical surgery provides a reason-able treatment choice, it may be a reasonable alternative to extraction in the presence of failed nonsurgical endodontics with unfavorable anatomical features for traditional apical surgery (Cotter and Panzarino). Key treatment recommendations for this procedure include atraumatic extraction, minimal handling of the root surface, an extraoral time of less than 10 minutes, biocompatible apical lls, and nonrigid postoperative splinting (Kratchman). Bender and Rossman reported a success rate of 81% for 31 intentional replantation cases.Fig 8-22 Harrison and Jurosky’s (1991a, 1991b) observations of postoperative healing after endodontic surgical intervention. PMN, polymorphonucleocyte.• Thin epi- thelial seal• Blood clot evident• PMN the predomi-nant inam-matory cell• Periosteal necrosis• Multi- layered epithelial seal• Type III collagen production• Macro-phages the pre-dominant inamma-tory cell• Clot replaced by granulation tissue• Type I collagen production • Osteocyte prolifera-tion from the endos- teum• Normal sulcular epithelium• Woven bony trabeculae occupy the wound• New periosteum evident• Maturing bony trabec-ulae occupy the woundDay 1Day 2Day 4Day 14Day 28http://dentalebooks.com 146Treatment of Endodontic Disease8Autotransplantation provides a replacement option for missing teeth under proper cir-cumstances. Though often used to replace lost teeth in the early permanent dentition (Cardona et al), a case report of autotransplantation of an incompletely formed, unerupted mandibular premolar into an articial socket in a patient with agenesis of a maxillary lateral incisor was recently published (Intra et al). Considerations for this therapy include patient age, occlusion, space available in the recipient site, and the anatomy of the donor tooth (Jonsson and Sigurdsson). Frequently, mandibular premolars are selected as donor teeth due to favorable anatomical features (Jonsson and Sigurdsson). Ideally, the donor tooth should have a partially developed root with an open apex (Lundberg and Isaksson). For successful autotransplantation, one must atraumatically extract the donor tooth to preserve the Hertwig epithelial root sheath and maintain the PDL cells for the recipient site (An-dreasen et al). Successful autotransplantation permits development of the donor tooth and continued growth of the alveolar bone and associated soft tissue (Lundberg and Isaksson). Vital Pulp TherapyVital pulp therapy serves to maintain the vitality of the radicular pulp tissue in cases of trauma, deep caries, iatrogenic damage, or in the presence of developmental anomalies. Maintaining pulp vitality, particularly in permanent teeth with open apices, is the treatment of choice as it promotes completion of root development. This process is often referred to as apexogenesis (AAE glossary). Several pulp therapies are available to practitioners to accomplish this goal, including pulp capping and both partial and full pulpotomies. This section will cover both of these treatment modalities. Pulp cappingPulp capping, according to the AAE glossary, involves “treatment of the exposed vital pulp by sealing with a dental material to facilitate the formation of reparative dentin and main-tenance of the vital pulp.” According to Bergenholtz, pulp caps should be placed as soon as an exposure occurs for the best prognosis. Other prognostic factors include patient age; exposure site, namely whether an axial or occlusal exposure occurs; and pulp capping material (Cho et al). Several pulp cap materials are available for practitioners, including MTA, CH, and Bio-dentine [Septodont]. Histologic responses to MTA and CH are similar (Iwamoto et al). The typical histologic response to both is coagulative necrosis followed by hard tissue bridging (Fig 8-23) (Torabinejad and Parirokh). These similar responses are likely observed because MTA forms CH upon setting (Parirokh and Torabinejad). Biodentine has recently been ad-vocated as an alternative to both materials. Nowicka et al found that Biodentine-capped pulps had a similar histologic appearance to those treated with MTA. Conversely, compos-ite restorative materials and their bonding agents are unacceptable pulp-capping agents. Silva et al found that leakage occurs when these materials are used due to bonding failures. Recent research highlights the ability of additional medicaments to facilitate healing af-ter pulp capping procedures. Karanxha et al found that simvastatin induced differentiation of human dental pulp cells when placed over pulp exposures. Furthermore, the same au-thors found that simvastatin also promoted odontogenesis. Additional research may push this medication from the realm of cholesterol treatment to vital pulp therapy. http://dentalebooks.com 147Vital Pulp TherapyPulpotomyPulpotomy treatment involves removal of the coronal portion of a vital pulp to preserve the vitality of the radicular pulp and can be either complete or partial, depending on the extent of coronal pulp tissue removed (AAE glossary). Pulpotomy treatment facilitates continued root development in immature permanent teeth (Cvek), or may offer effective emergency care in mature teeth until denitive care can be delivered. Asgary and Eghbal found that pain relief following pulpotomy treatment was greater than with a full pulpectomy in vital cases. However, this treatment is not without risk. Cvek found that common postoperative complications included calcication, internal root resorption, and complete pulpal necro-sis. After removing pulp tissue with a water-cooled high-speed handpiece (Cvek), several medicaments and restorative materials are available to cover the pulp tissue remaining in the roots. Historically, formocresol was often used during pulpotomy treatment, although this material is problematic for several reasons. Pashley et al found that formaldehyde en-ters the systemic circulation following formocresol pulpotomies, and Block et al found that formaldehyde-containing medications antigenically alter tissues and stimulate cell-mediat-ed responses. The AAE recommends avoiding formocresol and other products containing formaldehyde or paraformaldehyde, as they are both unsafe and ineffective. Consequent-ly, the continued use of this material in future care is unjustiable. Cvek used CH to cover pulp tissue stumps in his original work and found that it achieved predictable results. Bakland recommended instead that MTA be used for this purpose. Agui-lar and Linsuwanont found that both materials provided predictable treatment results. Lastly, research by Keswani et al found that platelet-rich brin was as effective a pulpotomy restor-ative material as MTA. A case illustrating an MTA pulpotomy is depicted in Fig 8-24. Pulp cap placedCoagulative necrosis of adjacent pulp tissueHard tissue bridge formedFig 8-23 Healing of pulp tissues following pulp-capping procedures with MTA or CH (Torabinejad and Parirokh).Fig 8-24 Preoperative (a) and immediate postoperative (b) radiographs of an MTA pulpotomy in a 10-year-old girl. (c) A 6-month follow-up radiograph dis-plays root thickening and continued apical closure. acbhttp://dentalebooks.com 148Treatment of Endodontic Disease8Though CH apexication achieves relatively predictable results (Jeeruphan et al), long-term CH apexication has been associated with an increased risk of cervical root fracture (Cvek). According to Cvek, the incidence of cervical root fracture following CH apexication is between 28% and 77%, depending on the extent of root development. This may result from the effect of CH on the physical properties of teeth. Andreason et al found that ex-tended CH application in sheep teeth signicantly weakened root structures. To combat the problematic effects of CH on dental structures, practitioners proposed the development of articial apical barriers. Given MTA’s biocompatibility and ability to seal in the presence of blood (Torabinejad and Parirokh), it was a natural choice for this application (Rafter). The use of articial barriers also signicantly decreases treatment times for patients. Simon et al found that even single-visit apexication treatment with MTA was possible. With-erspoon and Ham found that outcomes for MTA apexication completed in a single visit or over multiple visits were statistically equivalent. When MTA apexication is compared with CH apexication, outcomes are equivalent (Chala et al) or better (Jeeruphan et al). Conse-quently, MTA barrier placement offers an excellent alternative for patients in which follow-up may be problematic. An MTA apexication case is illustrated in Fig 8-26. ApexicationPulpal necrosis in an immature permanent tooth poses decided treatment challenges for practitioners. While a fully formed root apex instrumented properly creates a sufcient apical barrier for obturation, the open apices of incompletely developed roots require additional treatment to create a proper barrier. The treatment aimed at barrier creation is referred to as apexication (AAE glossary). The rst apexication technique described in the literature involved placement of CH into the root canal system allowing the Hertwig epithelial root sheath to generate an apical barrier (Frank). Kleier and Barr found that barriers typically form in an average of 1 year with a standard deviation of 7 months. In a review of the literature, Shabahang found that barrier formation may take as long as 24 months to form. Finucane and Kinirons recommended that CH be changed either every 3 months, every 6 to 8 months, or never during the apexi-cation process. A CH apexication case is illustrated in Fig 8-25. Fig 8-25 A CH apexication case. (a) A 12-year-old boy presented with a necrotic maxillary right central incisor with an open apex. A CH hard pack was placed (b), and a calcic barrier formed in 9 months (c). (d) Obturation of the canal space was completed with GP once barrier formation was complete. (Courtesy of Dr John Dresser, White River Junction, Vermont.)ac dbhttp://dentalebooks.com 149Regenerative EndodonticsThough apexication treatment preserves an immature permanent tooth, the treatment modality is limited by its inability to increase root thickness. Consequently, apexied teeth are more likely to experience root fractures than fully mature permanent teeth (Cvek). As a result of this risk, several strategies for reinforcement of apexied teeth have been sug-gested in the literature. Katebzadeh et al found that metal posts, opaque posts, and res-in-bonded posts all improved fracture resistance over unrestored teeth. Goldberg et al found that resin-modied glass ionomers reinforced tooth structure. Regenerative EndodonticsNecrotic immature permanent teeth pose specic challenges to practitioners, including the risk for fracture of thin root walls (Cvek). Consequently, alternatives to the apexication procedure have been investigated for a number of years. Regenerative endodontics refers to the “biologically based procedures designed to physiologically replace damaged tooth structures including dentin and root structures, as well as cells of the pulp-dentin complex” (AAE glossary). While early work by Nygaard-Ostby and Hjortdal brought this idea to the endodontic world, a case report by Banchs and Trope reignited excitement surrounding this treatment modality. According to Law, regenerative endodontics requires a necrotic pulp, an immature apex, no need for a post and core restoration, and parental compli-ance. Law asserted that the etiology of pulp necrosis is unimportant when considering this treatment modality. Recently, Colombo et al found that rapid attenuation of inammation is additionally necessary to facilitate repair. With proper case selection and adherence to scientically backed treatment protocols, regenerative endodontics may provide a reason-able alternative to apexication. Regenerative endodontics is, in essence, a tissue engineering procedure that facilitates development of dental hard tissues. According to Langer and Vacanti, requirements for tissue engineering include stem cells, growth factors, and a scaffold (Fig 8-27). Huang sug-gested that the scaffold and growth factors in regenerative endodontics are derived from the dentin, brin clot, and sterilized pulp tissue remnants. Lovelace et al showed that the mesenchymal stem cells that inltrate the canal space originate in the apical papilla. Fig 8-26 An MTA apexication case. (a) A 10-year-old girl presented with a necrotic maxillary left central incisor. An apical MTA plug was placed (b), and GP lling was inserted (c) at the same visit. acbhttp://dentalebooks.com 150Treatment of Endodontic Disease8Regenerative endodontic techniques facilitate both disinfection of the root canal space and ingrowth of stem cells capable of regenerating dental hard tissues. On access into the necrotic pulp space, Hargreaves et al recommended minimal instrumentation and the use of gentle irrigation to begin disinfection. Nagata et al found that the microbial prole of in-fected immature permanent teeth is similar to that found in mature permanent teeth. Con-sequently, irrigants like CHX and sodium hypochlorite are effective antimicrobials in these cases. Despite their efcacy, practitioners must balance antimicrobial efcacy and toxicity to stem cells. Trevino et al found that CHX reduced stem cell viability. Consequently, avoid-ance of CHX as an irrigant or intracanal medicament is indicated. High concentrations of sodium hypochlorite also reduce stem cell viability and differentiation (Martin et al 2014). Martin et al (2014) found that by using a lower concentration of 1.5% sodium hypochlorite solution followed by a rinse with 17% EDTA, cell viability improved. Other authors recom-mend the use of EDTA in irrigation protocols, including Trevino et al and Pang et al. Galler et al suggested that EDTA promotes release of growth factors in dentin. Consequently, EDTA aids in two of the three requirements for tissue engineering, namely the maintenance of stem cells and growth factor release, and its use is indicated in regenerative endodontic procedures. Following minimal instrumentation and irrigation, the placement of an intracanal me-dicament is indicated for a period of 2 to 4 weeks (Law). A similar balance between anti-microbial efcacy and stem cell toxicity must be achieved with medicaments as with irrig-ants. Hoshino et al found a triple antibiotic paste, combining ciprooxacin, metronidazole, and minocycline, eradicated endodontic microbes in vitro. Windley et al conrmed these Stem cellsScaffoldsTissue engineeringFig 8-27 The three factors necessary for tissue engineering to occur (Langer and Vacanti).Growth factorshttp://dentalebooks.com 151Regenerative Endodonticsndings in vivo in dogs. Clinical issues with this formulation, including staining of dental tissues attributed to minocycline, a tetracycline derivative (Kim et al), led to research into other antibiotic formulations. Thibodeau and Trope advocated a substitution of cefaclor for minocycline. Iwaya et al recommended a double antibiotic paste of metronidazole and ciprooxacin. Recently, Nosrat et al (2013) recommended Augmentin [GlaxoSmithKline] for disinfection purposes. Though antibiotic pastes are effective antimicrobials (Ordinola-Zapata et al), their negative effect on stem cell viability makes their use in regeneration protocols problematic (Ruparel et al). A promising alternative to these formulations is CH. Nagata et al found no difference in bacterial reduction between triple antibiotic pastes and CH. Ruparel et al found that while both double and triple antibiotic pastes in clinically useful concentrations reduced stem cell viability, CH did not. Furthermore, Althumairy et al found that CH promoted stem cell survival and proliferation. Consequently, CH may be better suited than antibiotic pastes as intracanal, interappointment medicaments for regenerative endodontic therapy. Disinfection of the root canal system by irrigants and intracanal medicaments precedes the introduction of stem cells, growth factors, and scaffolds into the root canal space. This is achieved by overinstrumentation into the apical papilla to stimulate bleeding (Banchs and Trope). Ideally, blood clots below the CEJ and is covered with an MTA ll. MTA is the cap material of choice; Mente et al found that it facilitates migration and proliferation of apical papilla stem cells. The blood clot beneath the MTA plug serves as the scaffold for migration of stem cells and development of hard tissues (Hargreaves et al). Recently, ad-ditional scaffolds have been investigated, including cross-linked collagen (Yamauchi et al 2011b), polylactic acid (Chandrahasa et al), and platelet-rich plasma (Jadhav et al). Petrino et al recommended placement of a collagen matrix such as CollaPlug [Zimmer] to prevent overextension of the MTA.A successful outcome after regenerative endodontic treatment includes both elimination of apical periodontitis and increases in both root length and width (Lenzi and Trope). Flake et al recommended that radiographic follow-up should include measurement of the radio-graphic root area. Recent prognostic investigations indicate that regenerative endodontics may predictably achieve these outcomes (Jeeruphan et al) (Fig 8-28). Fig 8-28 (a) A regenerative endodontic procedure on the mandibular left second premolar in a 12-year-old boy with a history of a fractured dens evaginatus resulting in pulpal necrosis with symptomatic apical periodontitis. (b) Minimal instrumenta-tion to the WL was performed during the rst visit, and bleeding into the canal space was achieved during the second visit. (c) An MTA plug was placed over the blood clot. ab chttp://dentalebooks.com 152Treatment of Endodontic Disease8Internal BleachingInternal bleaching techniques can effectively eliminate dentinal staining caused by intrapul-pal hemolysis and byproducts of endodontic infections (Glockner et al). Walton et al found successful removal of stains caused by tetracycline use during dentinogenesis. Furthermore, this technique may be effective for stains caused by MTA (Belobrov and Parashos). Spasser originally described the sodium perborate walking bleach technique. Nutting and Poe recommended the addition of Superoxol [Miltex], a 30% hydrogen peroxide solution, to sodium perborate for added efcacy. However, Madison and Walton found that both Super-oxol and heat were associated with an increased risk of resorption. Friedman recommended that water be used in place of Superoxol to minimize these risks. Rotstein et al advocated the placement of a 2-mm base at the CEJ to further reduce the risk of resoprtion, as the pre-sumed pathway for irritants to create the feared invasive cervical root resorption would be through exposed tubules at the level of the junctional epithelium and CEJ. Several authors have investigated the nature of the intracanal hard tissues formed follow-ing regenerative endodontic procedures. Wang et al found that they resemble cementum, PDL, and bone. Likewise, Becerra et al found brous connective tissues, cementum, and PDL. Yamauchi et al (2011a) found that hard tissue is found both associated with the dentin and separately in the canal space. Similarly appearing tissues are produced when plate-let-rich plasma scaffolds are used (Martin et al 2013, Torabinejad et al). Though promising, regenerative endodontic therapy is not without risk (Fig 8-29). Nosrat et al (2012) found that postoperative issues may include caries, short roots, discoloration, and canal calcication. The discoloration can result from either the use of minocycline (Kim et al) or the MTA plug (Felman and Parashos). Further study is indicated to mitigate these risks. A recent survey by Manguno et al indicates that dentists are becoming more accepting of regenerative endodontics, and many wish for additional training. Consequently, it be-hooves the endodontic specialist to both maintain current knowledge of this therapy and educate their referral base regarding treatment possibilities. Fig 8-29 Potential complications following regenerative endodon-tic therapy.Canal calcicationReinfectionShort rootsDiscolorationCarieshttp://dentalebooks.com 153Restoration of Endodontically Treated TeethFollow-Up CareThe majority of published studies, including those by Friedman and Mor and also Orstavik, indicate that patients receiving nonsurgical endodontic therapy should have, at minimum, a 1-year postoperative follow-up examination. Orstavik recommended using a standard-ized technique, particularly the periapical index (PAI) score, for determining radiographic healing. One year, though, may prove insufcient for denitive determination of success or failure, as many lesions require additional time to heal. Murphy et al found that 70% of lesions take more than 1 year to heal. Molven et al echoed these ndings by suggesting that lesions may take between 10 and 20 years to heal. For lesions unhealed at the 1-year mark, Yu et al found that 57% improved over time, while 31% worsened. Predictors for worsening included recall lesion size, pain on biting at recall, history of a postobturation are, and nonideal root canal length. Just as nonsurgical endodontic treatment should receive follow-up care, so should sur-gical treatment. According to Rud et al, surgical patients should be examined 1 year post-operatively. Echoing Rud et al’s statements, Song et al found no differences in outcomes when teeth were examined 1 or 4 years postoperatively. Rubenstein and Kim found that, for those teeth healed at early examination periods, the periapical status remained stable when followed for several years. Restoration of Endodontically Treated TeethDenitive restorative treatment following endodontic therapy is essential. The placement of a well-sealed restoration prevents percolation of oral uids and bacteria around the obturation material. Swanson and Madison found that oral uids reached the apex of end-odontically treated teeth in as little as 3 days with exposure to the oral environment. How-ever, Torabinejad et al found that leakage down the root canal space required 3 weeks. These ndings illustrate the necessity of both temporary and permanent restorations. Restorative treatment is also indicated because endodontic therapy may affect the phys-ical properties of the teeth, including stiffness and moisture content. These alterations may make teeth more susceptible to fracture. Reeh et al found that endodontic therapy reduced tooth stiffness by 5%, exclusively related to the access opening. Restorative pro-cedures resulted in further loss of stiffness by as much as 60% with preparation across both marginal ridges. Helfer et al found that the calcied tissues of pulpless teeth contain 9% less moisture than healthy teeth. Though stiffness and moisture content is affected by endodontic treatment, a review by Cheron et al concluded that dental hardness is not. Re-gardless of these ndings, protection of the teeth with adequate restorations is essential to mitigate the effects of endodontic therapy on the physical properties of teeth. Restorative care is not only necessary to mitigate the effects of endodontic treatment on dental physical properties, but also because outcomes of endodontically treated teeth are signicantly inuenced by restorative care (Fig 8-30). Chugal et al demonstrated a signi-cant reduction in failures in permanently versus temporarily restored teeth, again illustrat-ing the importance of denitive restorative care. The type of denitive restoration placed can inuence treatment outcomes based on tooth type. Sorensen and Martinoff found that outcomes of pulpless maxillary and mandibular premolars and molars were improved http://dentalebooks.com 154Treatment of Endodontic Disease8PostsPosts enhance retention of the coronal restoration and may be used in the restorative treatment of endodontically treated teeth. Posts should either equal the length of the clinical crown or measure two-thirds of the root length, whichever is longest (Shillingburg). Furthermore, posts should measure no wider than the size of a no. 3 Gates Glidden drill to prevent excessive dentin thinning (Kuttler et al). When placing a post, rubber dam isolation should always be used, as Goldfein et al demonstrated that outcomes are signicantly inuenced by their use. Posts should be used only when necessary as they neither improve the strength of end-odontically treated teeth nor long-term outcomes. Their weakening effects may result from the destruction of tooth structure caused by post preparations. Katz and Tamse found that by full coronal coverage. Outcomes of anterior teeth, however, were not signicantly improved by full-coverage restorations. Restorative treatment must respect the biologic width, and full-coverage restorations should en-compass a ferrule of tooth structure. Restorations that violate either principle may cause early periodontal or restorative failures. Biologic width, dened by Gargiulo et al as the minimally acceptable distance between the crown margin and alveolar crest, should total 3 mm. The biologic width comprises the combined gingival sulcus depth, epithelial attachment, and connective tissue attachment (Fig 8-31). Restoring clinicians should maintain this buffer between restoration margins and the alveolar bone. Violation of the biologic width leads to periodontal inammation and bone loss. The fer-rule refers to a 1.5- to 2-mm circumferential vertical wall of tooth structure encompassed by full-coverage restorations. This feature, described in a review by Juloski et al, decreases the fracture rate of endodontically treated teeth by providing both retention and resistance of the crown to displacement. Respecting both the biologic width and the ferrule effect can dramatically improve restorative outcomes of endodontically treated teeth. Gingival sulcus depthEpithelial attachmentConnective tissue attachmentBiologic width (3 mm)Fig 8-31 The anatomical features that contribute to the biologic width. This is the distance that the re-storing dentist should maintain between the restoration margin and the alveolar bone (Gargiulo et al).Improve outcomesReduce the impact of endodontic therapy on the physical properties of teethPrevent coronal leakage around the obturation materialFig 8-30 Common reasons cited to restore endodontically treat-ed teeth.http://dentalebooks.com 155Restoration of Endodontically Treated TeethDespite the associated risks, post placement may be necessary to improve retention of coronal restorations in certain cases. Controversy exists regarding both the timing and the method of preparing space for posts. Though Bourgeois and Lemon found no signi-cant difference between initial and delayed preparation, Fan et al found that delayed post preparations resulted in greater leakage than those prepared immediately. Madison and Zakariasen found no differences in leakage when post spaces were prepared with reamers, heat, or chloroform on les. Mattison et al found that mechanical and thermal post prepa-rations resulted in signicantly less leakage than those prepared with chloroform. Without a clear consensus in the literature, it is clear that the timing and method of post placement should be at the discretion of the provider. Endodontic treatment versus implantsAdvances in implant technology provide dentists with a predictable option for replacing missing teeth. Implants provide patients and clinicians with an excellent option when faced with heroic and risky dental treatment. Studies show that both implants and endodontic when post spaces were prepared in the buccal roots of premolars, the remaining dentin thickness was often less than 1 mm. Sagsen et al found that ber post systems, theo-retically expected to improve root strength, did not reinforce the endodontically treated teeth under study. Just as posts do not buttress endodontically treated teeth, they do not improve long-term outcomes. In a clinical study of teeth restored with posts, Sorensen and Martinoff found that intracoronal reinforcement did not signicantly increase the clinical success rate of endodontic therapy. Doyle et al (2007) found that placement of a post ac-tually decreased the success rates of endodontically treated teeth. Not only do posts fail to improve tooth strength or outcomes of endodontically treated teeth, the removal of root canal lling material for their placement increases leakage of the obturation material. Abramovitz et al found that leakage was signicantly increased in roots prepared for posts versus intact root canal llings. Mattison et al found that 5 to 7 mm of re-maining GP exhibited signicantly less leakage than 3 mm. Consequently, they recommend-ed that at least 5 to 7 mm of GP remain in the root canal space when posts are to be placed. Common issues associated with post-retained restorations are summarized in Fig 8-32. Post preparation may weaken endodontically treated teethPlacement may negatively affect outcomesRemoval of obturation material increases leakageFig 8-32 Often-reported issues associated with post placement in endodontically treated teeth.http://dentalebooks.com 156Treatment of Endodontic Disease8treatment provide satisfactory results for patients. Gatten et al found high satisfaction rates in patients having undergone either implant therapy or root canal therapy.As both treatment options are agreeable to patients, treatment decisions should con-sider the prognosis of both therapies. In a systematic review, Iqbal and Kim found no dif-ferences in survival between root canal therapy and implant-retained restorations. These results echo those of Doyle et al (2006), who found no differences between the failure rates of matched pairs of endodontically treated and restored teeth and single-unit implants. The absolute failure rate of both therapies was 6.1%. Several factors inuence the progno-sis of both treatment options. Doyle et al (2007) found a signicant increase in the failure rate of both implants and endodontically treated teeth in smokers. An increase in failures, though nonsignicant, was found in diabetic patients. Interestingly, however, the presence of an endodontically treated tooth next to an implant did not alter the success rate of either treatment modality. As success rates and reported patient satisfaction are similar for both treatment mo-dalities, the decision to restore or extract a compromised tooth must be based on other factors. The AAE states that, when considering implant therapy or endodontic treatment, the decision to proceed with either treatment option must be based on factors other than outcome. Restorative choices must be based on case complexity or the patient’s individual health and preferences. Treatment of cracked teethThe diagnosis and treatment of cracked teeth can prove vexing for clinicians and patients alike. Cameron described cracked tooth syndrome, including both chewing discomfort on biting and release as well as unexplained pain in response to cold. Cracked teeth are often minimally restored or unrestored (Turp and Gobetti). Hiatt found a nearly equal distribution of cracked teeth in unrestored teeth and those with Class 1 and 2 restorations. Seo et al associated cracked teeth with a history of nonbonded restorations, such as amalgams. Hallmarks of cracked tooth syndrome are summarized in Fig 8-33. Unlike many entities responsible for pulpal symptoms, cracked teeth are often best treated by proper restorative care rather than endodontic therapy. Guthrie and DiFiore found that 89% of patients with cracked teeth treated with full-coverage restorations exhibited symptom elimination following placement of the temporary restoration. In a long-term study, Krell and Rivera found that only 21% of teeth with cracked tooth syndrome that were crowned ever developed irreversible pulpitis or pulpal necrosis. Consequently, in patients presenting with cracked tooth syndrome, referral to the re-storative dentist for a full-cov-erage restoration is the initial treatment of choice. Thermal sensitivityBiting discomfortHistory of restorative treatmentFig 8-33 Commonly encountered symptoms associated with cracked tooth syndrome.http://dentalebooks.com 157Ethics and the LawEthics and the LawDental professionals are tasked with providing excellent care to patients, all the while up-holding stringent ethical and legal standards. The American Dental Association (ADA) code of ethics notes: “Although ethics and the law are closely related, they are not the same. Ethical obligations may and often do exceed legal duties.” The ethical principles on which the ADA’s code is based include patient autonomy, nonmalecence, benecence, justice, and veracity (Fig 8-34). These principles represent the “aspirational goals of the profes-sion” and should guide the practitioner in every patient interaction (ADA).Dentists also must abide by both state and federal laws. Every dentist must be familiar with their individual state laws, which can often be obtained from state dental societies. Furthermore, dentists must uphold federal laws, including those that fall under the Oc-cupational Health and Safety Administration (OSHA) and the Department of Health and Human Services. OSHA regulates every workplace and establishes blood-borne pathogen standards, hazard communication regulations, ionizing radiation safety, the reporting of occupational injuries, electrical safety, and establishment of safety routes among other standards. Every dentist shares the responsibility of ensuring that these standards are up-held in their place of business. Dentists must protect the condentiality of patient records. This issue becomes increas-ingly complex with the development of new technology. The Health Insurance Portability and Accountability Act (HIPAA), under the US Department of Health and Human Services, establishes guidelines for the protections of protected health information (PHI) and out-lines punishments for violations. Every dentist is responsible for ensuring compliance with these statutes by themselves and their employees. ADACode ofEthicsPatient autonomyVeracityBenecenceNonmalecenceJusticeFig 8-34 Ethical principles outlined in the ADA Principles of Ethics and Code of Professional Conduct.http://dentalebooks.com 158Treatment of Endodontic Disease8BibliographyLocal AnesthesiaAggarwal V, Singla M, Miglani S, Ansari I, Kohli S. A prospective, randomized, single-blind com-parative evaluation of anesthetic efcacy of posterior superior alveolar nerve blocks, buccal inltrations, and buccal plus palatal inltrations in patients with irreversible pulpitis. J Endod 2011;37:1491–1494.Aggarwal V, Singla M, Miglani S, Kohli S, Irfan M. A prospective, randomized single-blind eval-uation of effect of injection speed on anesthetic efcacy of inferior alveolar nerve block in patients with symptomatic irreversible pulpitis. J Endod 2012a;38:1578–1580.Aggarwal V, Singla M, Miglani S, Kohli S, Singh S. Comparative evaluation of 1.8 mL and 3.6 mL of 2% lidocaine with 1:200,000 epinephrine for inferior alveolar nerve block in patients with ir-reversible pulpitis: A prospective, randomized single-blind study. J Endod 2012b;38:753–756.Corbett IP, Kanaa MD, Whitworth JM, Meechan JG. Articaine inltration for anesthesia of man-dibular rst molars. J Endod 2008;34:514–518.Currie CC, Meechan JG, Whitworth JM, Corbett IP. 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