Volume 22.2 - SROMS – Selected Readings in Oral and

Transcription

SELECTED READINGS
IN
ORAL AND
MAXILLOFACIAL SURGERY
THE ART AND SCIENCE
OF CORONECTOMY
Kyriaki C. Marti, DMD, MD, PhD
Christos A. Skouteris, DMD, PhD
Volume 22, Number 2
April, 2014
The Art and Science of Coronectomy
Kyriaki C. Marti, DMD, MD, PhD and Christos A. Skouteris, DMD, PhD
INTRODUCTION
The method of coronectomy (partial odontectomy, or intentional third molar root retention)
has gained popularity in the last few years, and evidence-based research on this method is continually growing. The term coronectomy was introduced as “partial lower third molar odontectomy
with crown removal and deliberate vital root retention”.1 The intention of the technique has been
defined as “avoidance of nerve injury in cases of intimate relationship of the roots with the inferior
alveolar nerve”(IAN) as per the Hippocratic concept of “first, do not harm” (primum nil nocere).
The first publications on coronectomy appeared in 1984. A number of publications followed in
which detailed techniques, potential complications and short-term outcomes were presented.2-11
The primary benefit of coronectomy was avoiding IAN injury during third mandibular molar
removal, a complication that, although relatively rare, may have serious medico-legal implications.
Damage to the inferior alveolar nerve
associated with third molar removal is primary related to intraoperative mechanical injury.12-14 According to the literature the IAN
is the most commonly injured nerve (61. 1%)
followed by the lingual nerve (LN) (38.8%).15
Although more than half (69 %) if IAN injuries are related to third molar surgery,16 the
incidence of IAN injury still remains high
(42.9%-52.5%) when all types of oral surgical procedures (e.g., orthognathic, implant
surgery, and local anesthesia) are considered.17,18
dental follicle, and pericoronitis.20 Thus,
removing the dental crown while leaving the
roots addresses these problems while avoiding potential injury of the IAN.
Vital root retention, done either intentionally for alveolar bone preservation or
for IAN injury prevention has been successful as long as the roots remain isolated from
the oral environment and normal soft tissue
and osseous healing occurs over the coronal
surface.6,21,22 The purpose of this paper is to
review the recent literature on coronectomy
and present a step-by-step surgical technique
of coronectomy we use.
The IAN is frequently in very close
proximity to the roots of the mandibular third
molar and this possibility has to be carefully
assessed before surgery.19 The rationale for
coronectomy is based on the fact that the
crown of a fully or partially impacted third
mandibular molar is primarily responsible
for the periodontal health and root resorption
of the second molar, the formation of odontogenic cysts and tumors from the retained
SROMS
OBJECTIVES
1. Present the radiographic criteria
demonstrating an intimate association
of the roots of mandibular third molars
with the IAN.
2. Underscore the need for further
detailed imaging with cone-beam CT
2
VOLUME 22.2
Art and Science of Coronectomy
K.C. Marti, DMD, MD & C.A. Skouteris, DMD, PhD
(CBCT) that could assist the surgeon
in more clearly identifying high-risk
patients in whom coronectomy may be
indicated.
3. Present the surgical technique
of coronectomy in cases where there is
high risk of IAN injury and the rationale
behind each step of the procedure.
4. Discuss the pertinent literature
and the appropriate management of
complications of coronectomy.
METHOD
According to the literature, identification of the high-risk patient is a crucial part
of treatment planning for a coronectomy
procedure.23 Depth of impaction, horizontal
tooth position and proximity to the IAN c anal
(>2 mm) are predictive factors for IAN damage.24-26 Additionally, patient’s age and root
development are related to IAN sensory deficits.27 (Table 1)
Imaging
The panoramic radiograph is the standard imaging most often used for patient
screening and as an essential diagnostic tool.
CBCT is generally reserved for more detailed
____________________________________
Table 1: Factors predisposing
to Nerve damage
Surgeon’s experience
Surgical technique
Patient’s age
Third molar anatomy
Preexisting pathology
SROMS
3
imaging when indicated.23 The specificity
and sensitivity of the panoramic radiograph
to predict IAN injury is controversial with
reported ranges of 30% to 98% for specificity
and 24% to 66% for sensitivity.22,28
For patients identified as high-risk a
CBCT is the imaging modality of choice.
When CBCT is compared to panoramic
radiography for assessing the proximity of
the IAN to the impacted mandibular molar,
the specificity and sensitivity are 93% and
77% for CBCT and 70% and 63% for panoramic images.29
According to recent literature, CBCT
imaging is an excellent tool for assessment
of impacted tooth location, actual size, and
tooth relations to other anatomical structures
(e.g., IAN and the lingual plate of the mandible) in three dimensions. The radiation
exposure is equivalent or slightly higher that
traditional imaging. A benefit-to- risk assessment and financial costs should be taken in
consideration.30
In order to ensure the appropriate use
of CBCT for third molar surgery, the specific panoramic radiograph criteria for LD____________________________________
Table 2: Specific Panoramic
Radiographic Criteria for LDCBCT
Diversion of the inferior alveolar canal
Darkening of the roots
Interruption of the white line of the canal
Narrowing of the canal
Deflection of the roots
Juxta apical area
VOLUME 22.2
A
D
B
E
C
F
Figure 1. Specific panoramic radiographic criteria for LD-CBCT. A. Diversion of canal; B. Interruption of white line;
C. Darkening of the roots; D. Narrowing of canal; E. Deflection of the roots; F. Juxta apical area
SROMS
4
VOLUME 22.2
CBCT (Low Dose-Cone Beam-CT) have
been determined by previous authors,31 and
are listed in Table 2 and Figure 1 on the previous pages.
Juxta apical area, a new radiographic
sign, is a well-circumscribed radiolucent
area lateral to the root rather than at the apex.
MRI and CT studies have elicited that this is
likely to be a continuity of the IAN lamella
with the periodontal lamina dura of the adjacent tooth.23 (Fig. 1F) Darkening of the root
or the presence of two or more radiographic
signs were positive predictors of a postoperative IAN deficit.32 As far as risk assessment
for IAN injury is concerned, Gaeminia, et
al. showed that CBCT contributes to optimal
risk assessment and, as a consequence, to
more adequate surgical planning, compared
with panoramic radiography.34
Recently Renton, et al. identified
a nother group of patients that may benefit
from preoperative CBCT assessment and
a coronectomy procedure. In this group of
patients the lingual plate of the mandible is
completely absent and the IAN is actually situated between the lingual aspect of the tooth
and the mucosa.35
CBCT imaging can further help in the
selection of the best surgical approach. (Fig. 2
on P. 5) CBCT can be a useful tool to exclude
from the coronectomy group cases associated
with pathology as well as cases in which a
coronectomy is not really needed.36 Surgical
extraction of teeth associated with osseous
pathology has an increased risk of iatrogenic
injury to the IAN.
SROMS
5
Patient Selection and Informed Consent
Patient selection also excludes cases of
active infection, mobile or non-vital teeth,
teeth with incomplete root formation, and
cyst associated teeth. However, a recent publication reports that teeth associated with
dentigerous cysts may also benefit from a
coronectomy procedure.37 Immunocompromised patients and patients scheduled for
radiation therapy are not candidates for this
procedure.1,38,39 Age does not seem to affect
the outcome. A recent paper proposes the use
of coronectomy as a favorable technique for
patients over 40 years of age, presenting for
third molar surgery with a high probability of
IAN injury.40
Informed consent should be completed
in detail. The rationale for the procedure,
potential intra-operative complications, postoperative sequelae, appropriate management
of complications, and possible second stage
intervention will also have to be discussed.41
CBCT is an excellent educational tool for the
patient, allowing for a better understanding
of the rationale behind the procedure.
Surgical Technique
Coronectomy is a technique requiring
meticulous preoperative preparation of the
surgeon, assistants, and the patient. The technique has a long learning curve and should
not be considered as a “less invasive third
molar removal” but as a new approach with
specific technical demands and indications.
VOLUME 22.2
A
D
B
E
Figure 2. CBCT images that help selection of the best
surgical approach. A. Narrowing and deflection of the
IAN canal; B. Intimate association of IAN with the
root apex; C. Significant narrowing of the IAN canal;
D. A horizontally impacted third molar. Coronectomy
in this case can be challenging; E. Close association of
the crown of the third molar with the IAN. Cornonectomy in this case is contraindicated..
C
SROMS
6
VOLUME 22.2
The surgical technique of coronectomy
has some similarities with a conventional
odontectomy for third molar removal. Essential steps of the procedure include: adequate
exposure of the third molar, meticulous technique, and precision in the completion of the
partial odontectomy with minimal application of force.
There seems to be no consensus regarding the administration of antibiotics in the
preoperative and postoperative period following coronectomy.20 We routinely prescribed
postoperative antibiotics only for partially
impacted third molars with an indication
for coronectomy. The concern of possible
infection from the root remnant secondary to
pulp necrosis is not substantiated by recent
studies.42 It has been showed that endodontic
treatment does not prevent the possibility of
infection and therefore is not required as part
of the procedure.43
A
B
Coronectomy can be performed under
local anesthesia or under local anesthesia with
IV sedation. Due to the precision required
for the procedure, patient compliance, cooperation and comfort are a prerequisite for the
successful completion of the coronectomy.
A conventional mucoperiosteal flap
is reflected. It is critical that wide exposure
of the area be achieved, because adequate
removal of buccal and minimal distal alveolar bone should be performed. The crown of
the tooth should be exposed, extending 2 mm
below the cemento-enamel junction. Complete, unobstructed visualization of the anatomical crown of the third molar is required
before sectioning.
SROMS
7
C
Figure 3. 45-degree beveling of crown sections.
A. Schematic representation of crown sectioning;
B. Intraoperative view of completed crown sectioning; C. View of the crown showing the 45-degree
bevel.
VOLUME 22.2
Crown sectioning should be done in
such a manner to optimize the outcome of the
coronectomy. We prefer to carry out the procedure under loop magnification (x 2.5) for
more accuracy and precision. With the use
of a fissure bur, the crown sectioning should
be performed at a 45° bevel, starting 2 mm
below the cemento- enamel junction through
the pulpal cavity until a thin layer of enamel is
left lingually.(Fig. 3, on P. 6) This is essential
for protection of the lingual nerve that may
be situated between the lingual mucosa and
the lingual enamel wall of the crown. The
45° beveled sectioning of the crown ensures
that the level of the odontectomy is below the
course of the lingual nerve, thus minimizing
the possibility of injury. The crown is then
separated from the roots with minimal force.
If the cut is not deep enough it may result
in unintentional mobilization of the root or
in unfavorable sectioning of the crown thus
increasing the difficulty of the procedure.44-46
If a thin lingual enamel wall remains
attached to the root, it can be carefully
removed with the use of the bur. At the end
of the sectioning, the root surface should
be adequately below the buccal crest of the
socket. If this has not been accomplished,
further root surface reduction, 2 mm to 3 mm
below the buccal crest needs to be performed.
Root reduction below the buccal crest of the
socket seems to facilitate bone healing over
the root remnant.9
______________________________________________________________________________
A
B
C
D
Figure 4. T-sectioning of a crown. A. Third molar in space restriction; B. T-sectioning of the crown; C. The sectioned
crown with the dental follicle; D. Root remnant after crown removal.
SROMS
8
VOLUME 22.2
In cases where the sectioning of the
crown is difficult due to space restrictions,
multi-sectioning of the crown can be performed, allowing removal of the crown in
two separate pieces.45 Our preferred method
of sectioning in this instance is T-sectioning
of the crown. (Fig. 4 on P. 7)
As a means of preventing possible
infection due to pulp necrosis, we proceed
with ablation of the exposed pulp and subsequent spot welding at the orifices of the root
canals with a diode contact fiberoptic laserprobe (Wavelength= 980 +/- 10 nm). The settings that we use for the procedure are: Power: 1.5 W CW, 400 μm fiber, exposure time
for spot welding: 5 seconds of radiation followed by 5 seconds of rest period.47,48 This
very short exposure of the coronal part of the
root remnant to the laser beam ensures a minimal change of the root temperature, which
is lower than the safe exposure temperature
for the soft and hard tissues around the root
remnant.49-53 (Fig. 5)
The wound is then irrigated with copious
amounts of normal saline solution. Wound irrigation is always an important step of the surgical wound care. It is particularly important
in coronectomy to irrigate the socket with
normal saline. Thus pulp remnants, bone,
and tooth debris are removed before wound
closure. The wound is closed in a watertight
fashion with interrupted vertical mattress
sutures (4-0 Vicryl Rapide®). This type of
wound closure provides adequate isolation of
the root remnant from the oral environment.36
(Fig. 6 on P. 9)
SROMS
9
A
B
C
Figure 5. Laser pulpotomy. A. Laser ablation of the
exposed pulp; B. Intraoperative view after pulp ablation and; C. After spot welding at the orifices of the
root canals.
VOLUME 22.2
MANAGEMENT OFCOMPLICATIONS
Intraoperative and immediate
postoperative complications
Figure 6. Soft tissue closure with interrupted vertical
mattress sutures
____________________________________
Postoperative management
Analgesics and chlorexidine gluconate
0.12% oral rinse should be prescribed. The
patient has to be aware of the importance of
the next follow-up visits including a panoramic radiograph in 12 months. Re-evaluation of the patient is advised in case of symptoms or root eruption.
Some authors33,38,39,46 use antibiotics
postoperatively to reduce risk of infection.
Other authors consider that there is no need
for routine antibiotic use for this procedure,
unless pericoronal infection is present.32,41
As previously mentioned, we routinely administer antibiotics only in cases of partially
impacted third molars with an indication for
coronectomy.
All the important steps of the procedure
are recorded, in a detailed operative note. It
is advisable that a letter be sent to the referring dentist with information about the surgical procedure, its rationale, the follow-up
schedule, and all possible early and late complications including possible second stage
intervention.
SROMS
10
A technique-specific complication is the
mobilization of the root segment during coronectomy, which can result in failure (immediate or delayed) of the procedure. In order to
prevent this complication, crown-root separation after sectioning should be performed
with the application of minimal force. Excessive force may result in mobility of the root
remnant especially in cases of cone-shaped
roots. This will lead to removal of the root
during the procedure and consequently to
coronectomy failure and possible IAN injury.
According to Gady and Fletcher, root
mobilization may initiate fast migration and
eruption of the root.38 Renton, et al. showed
that small conical roots in female patients
are prone to mobilization and utmost care is
required to avoid this complication.41 However, Leung and Cheung reported that no significant risk factors were found to be associated
with coronectomy failure (in terms of age,
sex, root shape, pattern and depth of impaction).54 The overall failure rate for coronectomy has been reported to range from 2.3%
to 38.3%.10,33,36,39,54,56
One of the most common early complications of coronectomy is dry socket.
This can result in delayed healing, infection,
and need for root extraction.41 The reported
incidence of dry socket ranges from 10% to
12.1%.10,33,54,55 Treatment of this complication
includes the use of chlorexidine oral rinse
and application of resorbable dressings.
VOLUME 22.2
Other contributors to delayed healing are retention of enamel, root mobilization, and wound dehiscence.55 Isolation of
the root remnant from the oral cavity is very
important. Experimental data from a study on
submerged roots showed that roots need to
remain totally covered by soft tissue in order
to be eventually covered by bone.58
There are conflicting data relative to
patient perception of postoperative pain.

Some studies comparing the conventional
extraction techniques with coronectomy
have reported less pain for the coronectomy
group compared with the control group.54,57
This was attributed to removal of a smaller
amount of bone. In one study the postoperative pain was of higher intensity in comparison to the control group.33 In a case of prolonged intermittent pain the root remnant had
to be removed. The second stage procedure
was safely performed because the root had
moved away from the IAN.40
Reported incidence of infection after
coronectomy ranges from 0.98% to 5.2 %.10,
33,58
This is usually treated with broad-spectrum antibiotics, anti-inflammatory medications, and socket irrigation. If the infection
resolves in a few days, no further treatment
is required.55 If the patient returns with persistent or recurrent infection consideration
should be given to removing the roots.33,41
Late Complications
Root migration is considered a late complication of coronectomy with prevalence
estimates varying from 13.2% to 85.29%.8,9,
10,33,43,54
Upward root migration occurs primarily during the first year, particularly dur-
SROMS
11
ing the first 6 months, and is generally completed after 2 to 3 years as the bone remodels.
Leung and Cheung reported that in more
than half of their cases there was migration of
the root remnant. This occurred rapidly during the first 3 months and then gradually subsided after 12 to 24 months (mean distance of
migration 3.06 mm).54
In a more recent study with a 3-year
follow-up, the same authors reported a mean
root migration distance of 2.8 mm.57 No further root migration occurred between the
24th and the 36th month, with the exception
of four roots that erupted and were removed.
There was a statistically higher mean migration distance in women that in men (3.4 mm
vs. 2.4 mm).
In a group of 102 coronectomies with
a mean follow-up of 13.5 months, Hatano,
et al. reported root migration of 85.3%.33
Dolanmaz, et al. reported that the movement
of the root remnants reached its maximum in
the first postoperative 6 months (mean, 3.4
mm), while they recorded a high migration
rate (85%).43 Pogrel reported a 30% prevalence (150 cases) of root migration within
a year. Nine roots erupted and needed to be
secondarily removed.59
In our group of patients bone healing over the retained root was complete 12
months postoperatively. The incidence of
root migration was 4.1 %. The asymptomatic
migration did not lead to removal of the root
remnant. (Fig. 7 on P. 11)
Leung and Cheung, in a 3-year followup study, reported that root eruption caus-
VOLUME 22.2
A
B
C
D
Figure 7. Asymptomatic root migration does not
reqjuire removal of the remnant. A. Preoperative and
B. postoperative view of uneventful bone healing
over the retained root; C. Root remnant showing no
migration 12 months after coronectomy; D. Preoperative view of an impacted third molar with a juxta
apical area; E. Postoperative view showing the root
migration 12 months after coronectomy.
E
______________________________________________________________________________
ing symptoms and leading to removal of the
remnant occurred in 3% of the cases.57 There
is a general consensus that roots should be
removed either when they erupt or when
SROMS
12
they are symptomatic. The important issue
about this migration is that the root remnant
is moving away from the IAN canal, allowing for a “safer” delayed removal of the root
VOLUME 22.2
with a simple procedure usually under local
anesthesia. There is one report in the literature about a very unusual case where a root
remnant erupted entraining along with it the
IAN canal.60
No pathology associated with the root
remnant has been reported so far and no osteomyelitis or mandibular fractures have been
associated with this type of surgery. Nerve injury due to coronectomy is considered a very
rare complication. Renton et al.10 and Cilasun
et al.39 report no IAN injury, while Leung and
Cheung54 and Hatano, et al.33 reported IAN
impairment in 1 out of 155 and 102 cases,
respectively.
The lingual nerve is less commonly
injured during conventional third molar surgery, but when that occurs the damage to the
nerve is more severe.17 There are no reports
of lingual nerve (LN) injury during coronectomy, except for one case of transient impairment of the LN reported by Pogrel et al,
which was attributed to lingual retraction.59
An interesting radiographic finding
associated with coronectomy has been the
asymptomatic “apical radiolucency” which
presents under the apical part of a migrating
root, especially in the first three months.64
This radiographic feature while it may give
the impression of apical pathology is considered benign and is believed to be due to delayed regeneration of bone.
O’Riordan followed-up radiographically two cases with this finding and reported
that the apical radiolucency remained evident
2 years after coronectomy.11 The lamina dura
was visible around the apex of the remnant.
SROMS
13
DISCUSSION
In view of the recent advances in imaging, avoidance of nerve damage is feasible.
According to Renton, litigation is often based
on inadequate consent procedure, inadequate
planning and assessment, causation of avoidable nerve injury, and poor management of
the patient once nerve injury has occurred.61
Transient involvement of the IAN as a complication after third molar surgery ranges
from 1% to 5 %, and permanent deficit ranges from 0.04% to 25%.15 A self-reported rate
of nerve injury (temporary and permanent)
by oral surgeons was 4 per 1,000 lower third
molar extractions for the IAN and 1 per 1,000
extractions for the LN. Self-reported rates
of permanent injury were 1 per 2,500 lower
third molar extractions for the IAN and 1 per
10,000 lower third molar extractions for the
LN.62
When imaging risk factors are present,
incidence of nerve involvement has been
reported as high as 12%. The most common
cause of IAN injury (requiring intervention)
is third molar surgery (52%) according to Tay
and Zuniga.17 Patients present with paresthesia as the most common symptom. Dysesthesia and allodynia have also been reported and
are very debilitating.63
Bataineh reported higher incidence of
nerve injury in the under 20-year-old group
of patients and that injury was significantly
related to the operators’ experience.24 Cheung
, et al. associated nerve impairment with the
depth of impaction and lack of experience.25
Factors found to be associated with a significantly higher incidence of IAN paresthesia
include patients in the 26- to 30-year age
VOLUME 22.2
group, horizontal impactions, root development, close proximity to the inferior alveolar
canal and operator experience.26,27
Some authors discuss the potential difficulty of properly sectioning horizontally
impacted teeth, without jeopardizing the IAN
that may lie in close proximity to the mesial
aspect of the horizontally impacted tooth.
These cases should be carefully evaluated
before surgery with the use of a CBCT.
Gady and Fletcher argued that a horizontal impaction is a contraindication for
coronectomy.38 Pogrel also considered these
cases as being unsuitable for coronectomy.46
Hatano, et al. included horizontally impacted
third molars in their series of cases, stating
that crown section can often be complicated.33 We do not feel that horizontally impacted molars are always unsuitable for coronectomy. However, “safe” sectioning of the
crown of a horizontally impacted tooth may
be technically very challenging.
root canals, thus preventing any contact of the
oral cavity with the radicular dental pulp.51-53
Our experience with a group of 24 cases of
coronectomy with laser ablation, showed that
within a 12-month- follow up there was no
incidence of infection or other complications.
There is strong evidence in the literature that treatment of the exposed pulp is
not required.31,46 Sencimen, et al. in a study
comparing the endodontically treated root
remnants to non-treated retained roots after
coronectomy showed that endodontic treatment of the tooth remnant does not affect the
success of the method.43
An important late sequela of coronectomy is root migration. Maintaining the occlusal surface of the root remnant 2 mm to
3 mm inferior to the crest of bone appears to
prevent eruption of the root into the oral cavity. This 3 mm distance also appears to facilitate bone formation over the retained root
fragment.1,9
Competence in a surgical procedure is
a combination of training and experience. A
learning curve is needed for a procedure that
has been relatively recently introduced to the
oral surgery practice. Coronectomy remains
a technique-sensitive procedure.1,64
According to Whitaker, et al. submerged
root segments remain vital and the majority
of them sustain coronal bridging. Coronal
bridging refers to circumferential closure of
the coronal rim of the pulp canal by calcified
tissue, without any sign of inflammation.58
On the issue of endodontic treatment of
the exposed pulp, our rationale for the use of
a diode laser for pulpotomy and spot welding of the orifices of the root canals was to
prevent infection secondary to pulp necrosis.
Laser pulp ablation is a procedure performed
routinely by endodontists mainly in primary
teeth, and it is considered a safe technique. It
allows complete sealing of the orifices of the
“Enamel lipping” is a term that describes
the retention of a fragment of enamel on the
root remnant, due to technical difficulty. It
occurs commonly in disto-angular impacted third molars with close proximity to the
second molar. The enamel lip can be seen
in a postoperative radiograph and it seems
to jeopardize the long-term retention of the
root, because the avascular enamel acts as a
SROMS
14
VOLUME 22.2
foreign body for the surrounding tissues and
may lead to a non-healing dry socket.65
Finally the most important question to
be answered is whether coronectomy offers
any benefit in terms of preventing IAN injury.
There are a few studies that compare the coronectomy group outcomes to a control group
of totally extracted teeth. Results from these
studies seem to be encouraging, for avoidance of IAN injury.55 Cilasun, et al, as well
as Renton, et al, reported no IAN injury in
the coronectomy group. Leung and Cheung
reported one case in the coronectomy group
(0.06%) and Hatano, et al. presented one case
of temporary impairment (1%). In the extraction group (43 patients out of 521 third molars) 8.3% were diagnosed with IAN injury.
The injury resolved in 35 patients within one
month after extraction. Eight patients (1.5%)
were diagnosed with permanent injury. The
pooled risk ratio for IAN injury indicates that
patients in the total-removal group would be
ten times as likely as those in the coronectomy group to suffer from IAN injury.10,33,39,54,56
Relative to complications such as dry
socket, infection, and postoperative pain, a
meta-analysis by Long, et al. of four studies
showed that the risk ratio for dry socket and
postoperative infection was similar between
coronectomy and total removal.56 Moreover
there was no difference in postoperative
pain at one week following coronectomy
compared to total removal. The limitations
reported in their study were: small number
of studies, no high-quality studies, heterogeneity among studies, and short length of
follow-up.56
SROMS
15
Recently a number of different
approaches have been proposed for treat
ment of high–risk third molars, with a proximity to the IAN. These include: orthodontic
extraction,66-68 pericoronal ostectomy,69 and
removal of the mesial portion of the anatomic
crown.70 It seems that more studies are needed to determine whether these approaches
offer any significant advantages.
CONCLUSION
Coronectomy has been employed in an
effort to reduce the incidence of iatrogenic
damage to the inferior alveolar nerve, in cases
of anatomic proximity of the roots of a third
molar to the mandibular canal. After careful
patient selection and when performed in a
meticulous manner, the technique is safe and
effective in reducing the risk of IAN injury.
Complications, other than IAN injury, associated with the method are similar to those
associated with impacted third molar removal. Coronectomy failure and root m
igration
requiring re-operation are the main technique-specific complications. Meticulous
planning of the procedure, documentation,
and a detailed informed consent are mandatory for legal considerations. There is no doubt
that further randomized controlled clinical
trials with long term follow-up are needed to
evaluate the adverse effects of coronectomy.
VOLUME 22.2
Kyriaki C. Marti, DMD, MD, PhD,
FEBOMFS, received her dental and PhD
Degree from the University of Thessaloniki
School of Dentistry, and her medical degree
from the University of Athens School of
Medicine, in Greece. She completed her residency in oral and maxillofacial surgery at the
University of Athens School of Dentistry.
Dr. Marti is a Fellow of the European Board
of Oral and Maxillofacial Surgery. She has
served as Assistant Professor, Department of
Oral and Maxillofacial Surgery, University of
Athens School of Dentistry, and as Visiting
Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, Medical
College of Virginia, Virginia Commonwealth
University. Dr. Marti is currently Adjunct
Clinical Assistant Professor, at the Department of Oral and Maxillofacial Surgery, University of Michigan School of Dentistry. Her
main clinical interests are dentoalveolar surgery, lasers, implants, and minimally invasive
cosmetic procedures. She is member of many
professional associations and she has many
publications (scientific papers, book chapters
and books) and numerous presentations in national and international meetings. Dr. Marti
has a strong interest in medical and dental
education and she has extensive experience
in basic and clinical teaching and instruction
of dental students, medical students and residents. Dr. Marti has been accepted in the
MHPE Program of the Department of Medical Education, University of Michigan Medical School, to pursue a Masters Degree in
Health Professions Education.
SROMS
16
Christos A. Skouteris, DMD, PhD, is a
graduate of the University of Athens School
of Dentistry. He completed a three-year training program in oral pathology at the same
university that led to a PhD degree and a sixyear residency in oral and maxillofacial surgery at the University of Pittsburgh School of
Medicine-Presbyterian University Hospital
in the USA. He served as teaching fellow at
the University of Pittsburgh School of Dental Medicine, as Visiting Assistant Professor
with the Department of Plastic, Reconstructive, and Maxillofacial Surgery at the University of Pittsburgh School of Medicine, as
Visiting Professor, Department of Oral and
Maxillofacial Surgery, School of Dentistry,
Medical College of Virginia, Virginia Commonwealth University, as Assistant Professor
of Oral and Maxillofacial Surgery at the University of Crete School of Medicine, and as
Associate Professor of Oral and Maxillofacial
Surgery at the University of Athens School of
Dentistry. Currently, Dr. Skouteris is Clinical
Assistant Professor, Department of Surgery,
Section of Oral and Maxillofacial Surgery,
University of Michigan Medical School and
Undergraduate Clinic Director, Department
of Oral and Maxillofacial Surgery University
of Michigan School of Dentistry. He is member of many professional associations and
has numerous publications (scientific papers,
book chapters and books) and presentations
in national and international meetings. Dr.
Skouteris has considerable experience in
clinical teaching and instruction of dental
students, medical students, and residents. His
clinical interests include oral oncology, TMJ
disorders, orthognathic surgery, trauma, secondary alveolar cleft repair, and minimally
invasive cosmetic maxillofacial surgery.
VOLUME 22.2
REFERENCES
1. Pogrel MA: Partial odontectomy. Oral
Maxillofac Surg Clin North Am 19: 85,
2007.
2. Ecuyer J and Debien J: Surgical deductions. Actual Odontostomatol (Paris). In
French. 38: 695, 1984.
3. Knutsson K, Lysell L and Rohlin M: Postoperative status after partial removal of
the mandibular third molar. Swed Dent
J 13:15, 1989.
4. Freedman GL: Intentional partial odontectomy: Report of case. J Oral Maxillofac
Surg 50: 419, 1992.
5. Freedman GL: Intentional partial odontectomy: Review of cases. J Oral Maxillofac Surg 55: 524, 1997.
6. Zola MB: Avoiding anesthesia by root
retention. J Oral Maxillofac Surg 51:
954, 1993.
7. Alantar A, Roisin-Chausson MH, Commissionat Y, et al: Retention of third
molar roots to prevent damage to the
inferior alveolar nerve. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 80:
126, 1995.
8. O’Riordan B: Uneasy lays the head that
wears a crown. Br J Oral Maxillofac
Surg 35: 209, 1997.
SROMS
17
9. Pogrel AM, Lee JS and Muff DF: Coronectomy: A technique to protect the inferior
alveolar nerve. J Oral Maxillofac Sur
62: 1447, 2004.
10. Renton T, Hankins M, Sproate C, et al:
A randomized controlled clinical trial to
compare the incidence of injury to the
inferior alveolar nerve as a result of coronectomy and removal of mandibular
third molars. Br J Oral Maxillofac Surg
43: 7, 2005.
11. O’Riordan BC: Coronectomy (intentional
partial odontectomy of lower third molars). Oral Surg Oral Med Oral Pathol
Oral Radiol Endod 98: 274, 2004.
12. Rossitti EO: Central and peripheral nervous complications of dental treatment.
Arq Neuropsiquiatr 53: 513, 1995.
13.Zuniga JR. Contemporary non-surgical
options for trigeminal sensory disorders.
Selected Readings in Oral and Maxillofacial Surgery , Vol.14, #1 ,2006
14. Zuniga JR , Miller DJ. Injection injury to
the third branch of the trigeminal nerve.
Selected Readings in Oral and Maxillofacial Surgery , Vol 20 ,#4, 2012.
15. Zuniga JR: Management of third molarrelated nerve injuries: observe or treat?
Alpha Omegan 102: 79, 2009.
16. Hillerup S: Iatrogenic injury to the inferior alveolar nerve: etiology, signs and
symptoms, and observations on recovery. Int J Oral Maxillofac Surg 37: 704,
2008.
VOLUME 22.2
17. Tay AB and Zuniga JR: Clinical characteristics of trigeminal nerve injury
referrals to a university centre. Int J Oral
Maxillofac Surg 36: 922, 2007.
24. Bataineh AB: Sensory nerve impairment
following mandibular third molar surgery. J Oral Maxillofac Surg 59: 1012,
2001.
18. Strauss ER, Ziccardi VB, and Janal MN:
Outcome assessment of inferior alveolar nerve microsurgery: a retrospective review. J Oral Maxillofac Surg 64:
1767, 2006.
25. Cheung LK, Leung YY, Chow LK, et
al: Incidence of neurosensory deficits
and recovery after lower third molar
surgery: a prospective clinical study of
4338 cases. Int J Oral Maxillofac Surg
39: 320, 2010.
19. Savi A, Manfredi M, Pizzi S, et al:
Inferior alveolar nerve injury related to
surgery for an erupted third molar. Oral
Surg Oral Med Oral Pathol Oral Radiol
Endod 103: e7, 2007.
20. American Association of Oral and Maxillofacial Surgeons Task Force. White
Paper on Third Molar Data, 2007 (http://
www.aaoms.org/docs/third_molar_
white_paper.pdf).
21. Fareed K, Khayat R and Salins P: Vital
root retention, a clinical procedure. J
Prosthet Dent 62: 430, 1989.
22. Gomes AC, Vasconcelos BC, Silva ED,
et al: Sensitivity and specificity of pantomography to predict inferior alveolar nerve damage during extraction of
impacted lower third molars. J Oral

23. Renton T: Iatrogenous injuries. Minimising and managing iatrogenous trigeminal nerve injuries in relation to dental
procedures. IN: Birch R (ed): Surgical
Disorders of the Peripheral Nerves (ed
2). London, England, Springer-Verlang,
2011, p.510.
SROMS
18
26. Jerjes W, Upile T, Shah P, et al: Risk factors associated with injury to the inferior alveolar and lingual nerves following third molar surgery-revisited. Oral
Surg Oral Med Oral Pathol Oral Radiol
Endod 109: 335, 2010.
27. Gülicher D and Gerlach KL: Sensory
impairment of the lingual and inferior
alveolar nerves following removal of
impacted mandibular third molars. Int J
Oral Maxillofac Surg 30: 306, 2001.
28. Susarla SM and Dodson TB: Preoperative computed tomography imaging in
the management of impacted mandibular third molars. J Oral Maxillofac Surg
65: 83, 2007.
29. Tantanapornkul W, Okouchi K, Fujiwara Y, et al: A comparative study of
cone-beam computed tomography and
conventional panoramic radiography
in assessing the topographic relationship between the mandibular canal and
impacted third molars. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod
103: 253, 2007.
VOLUME 22.2
30. Kapila S, Conley R S and Harrell, Jr WE:
The current status of cone beam computed tomography imaging in orthodontics. Dentomaxillofac Radiol 40: 24,
2011.
37. Patel V, Sproat C, Samani M, et al:
Unerupted teeth associated with den
tigerous cysts and treated with coronectomy: mini case series. Br J Oral Maxillofac Surg 51: 644, 2013.
31. Frafjord R and Renton T: A review of
coronectomy. Oral Surgery 3: 1, 2010.
38. Gady J and Fletcher MC: Coronectomy:
indications, outcomes, and description
of technique. Atlas Oral Maxillofac
Surg Clin North Am 21: 221, 2013.
32. Leung YY and Cheung LK: Correlation of radiographic signs, inferior dental nerve exposure, and deficit in third
molar surgery. J Oral Maxillofac Surg
69: 1873, 2011.
33. Hatano Y, Kurita K, Kuroiwa Y, et al:
Clinical evaluations of coronectomy
(intentional partial odontectomy) for
mandibular third molars using dental
computed tomography: a case-control
study. J Oral Maxillofac Surg 67: 1806,
2009.
34. Ghaeminia H, Meijer GJ, Soehardi A,
et al: The use of cone beam CT for the
removal of wisdom teeth changes the
surgical approach compared with panoramic radiography: a pilot study. Int J
35. Renton T, Yilmaz Z and Gaballah K:
Evaluation of trigeminal nerve injuries
in relation to third molar surgery in a
prospective patient cohort. Recommendations for prevention. Int J Oral Maxillofac Surg 41: 1509, 2012.
36. Renton T: Update on coronectomy. A
safer way to remove high-risk mandibular third molars. Dent Update 40: 362-4,
366-8, 2013.
SROMS
19
39. Cilasun U, Yildirim T, Guzeldemir E, et
al: Coronectomy in patients with high
risk of inferior alveolar nerve injury
diagnosed by computed tomography. J
40. Monaco G, de Santis G, Gatto MR, et
al: Coronectomy: a surgical option for
impacted third molars in close proximity to the inferior alveolar nerve. J Am
Dent Assoc 143: 363, 2012.
41. Renton T: Notes on coronectomy. Br Dent
J 13 212: 323, 2012.
42. Dolanmaz D, Yildirim G, Isik K, et al: A
preferable technique for protecting the
inferior alveolar nerve: coronectomy. J
43. Sencimen M, Ortakoglu K, Aydin C, et
al: Is endodontic treatment necessary
during coronectomy procedure? J Oral
44. Gleeson CF, Patel V, Kwok J, et al: Coronectomy practice. Paper 1. Technique
and trouble-shooting. Br J Oral Maxillofac Surg 50: 739, 2012.
VOLUME 22.2
45. Genú PR and Vasconcelos BC: Influence
of the tooth section technique in alveolar
nerve damage after surgery of impacted
lower third molars. Int J Oral Maxillofac
Surg 37: 923, 2008.
52. Odabaş ME, Bodur H, Bariş E, et al:
Clinical, radiographic, and histopathologic evaluation of Nd: YAG laser pulpotomy on human primary teeth. J Endod
33: 415, 2007.
46. Pogrel MA: Coronectomy to prevent
damage to the inferior alveolar nerve.
Alpha Omegan 102: 61, 2009.
53. De Coster P, Rajasekharan S and Martens
L: Laser-assisted pulpotomy in primary
teeth: a systematic review. Int J Paediatr
Dent 23: 389, 2013.
47. Schoop U, Kluger W, Dervisbegovic S, et
al: Innovative wavelengths in endodontic treatment. Lasers Surg Med 38: 624,
2006.
48. Gutknecht N, Franzen R, Meister J, et al:
Temperature evolution on human teeth
root surface after diode laser assisted
endodontic treatment. Lasers Med Sci
20: 99, 2005.
49. Hmud R,
perature
infrared

ment of
2010.
Kahler W and Walsh LJ: Temchanges accompanying near
diode laser endodontic treatwet canals. J Endod 36: 908,
50. Alfredo E, Marchesan MA, Sousa-Neto
MD, et al: Temperature variation at the
external root surface during 980-nm
diode laser irradiation in the root canal.
J Dent 36: 529, 2008.
51. Liu JF: Effects of Nd: YAG laser pulpotomy on human primary molars. J Endod
32: 404, 2006.
54. Leung YY and Cheung LK: Safety of coronectomy versus excision excision of
wisdom teeth: a randomized controlled
trial. Oral Surg Oral Med Oral Pathol
55. Patel V, Gleeson CF, Kwok J, et al: Coronectomy practice. Paper 2: Complications and long-term management. Br J
56. Long H, Zhou Y, Liao L, et al: Coronectomy vs. total removal for third molar
extraction: a systematic review. J Dent
Res 91:659, 2012.
57. Leung YY and Cheung LK: Coronectomy
of the lower third molar is safe within
the first 3 years. J Oral Maxillofac Surg
70:1515, 2012.
58. Whitaker DD and Shankle RJ: A study
of the histologic reaction of submerged
root segments. Oral Surg Oral Med Oral
Pathol 37: 919, 1974.
59. Pogrel MA: An update on coronectomy.
J Oral Maxillofac Surg 67: 1782, 2009.
SROMS
20
VOLUME 22.2
60. Drage N and Renton T: Inferior alveolar
nerve injury related to mandibular third
molar surgery: an unusual case presentation. Oral Surg Oral Med Oral Pathol
67. Wang Y, He D, Yang C, et al: An easy
way to apply orthodontic extraction for
impacted lower third molar compressing to the inferior alveolar nerve. J Craniomaxillofac Surg 40:234, 2012.
61. Renton T: Oral surgery: part 4. Minimizing and managing nerve injuries and
other complications. Br Dent J 215: 393,
2013.
68. Park W, Park JS, Kim YM, et al: Orthodontic extrusion of the lower third
molar with an orthodontic mini implant.
Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 110 :e1, 2010.
62. Robert RC, Bacchetti P and Pogrel MA:
Frequency of trigeminal nerve injuries
following third molar removal. J Oral
63. Hillerup S: Iatrogenic injury to oral
branches of the trigeminal nerve:
records of 449 cases. Clin Oral Investig
11: 133, 2007.
64. Geisler S: Coronectomy is an effective
strategy for treating impacted third
molars in close proximity to the inferior
alveolar nerve. J Am Dent Assoc 144:
1172, 2013.
65. Patel V, Kwok J, Sproat C, et al: To
retrieve or not to retrieve the coronectomy root. The clinical dilemma. Dent
Update 40: 370, 2013.
66. Alessandri Bonetti G, Bendandi M,
et al: Orthodontic extraction: riskless extraction of impacted lower third
molars close to the mandibular canal.
J Oral Maxillofac Surg 65: 2580, 2007.
SROMS
21
69. Tolstunov L: Pericoronal osteotomy
as
alternative treatment option for
extraction of impacted mandibular third
molars in proximity to inferior alveolar
nerve. J Oral Maxillofac Surg 68: 231,
2010.
70. Landi L, Manicone PF, Piccinelli S, et al:
A novel surgical approach to impacted
mandibular third molars to reduce the
risk of paresthesia: a case series. J Oral
RELATED ARTICLES IN SELECTED
READINGS IN ORAL AND MAXILLOFACIAL SURGERY
Contemporary Non-Surgical Options for
Trigeminal Sensory Disorders. John
R. Zuniga, DMD, MS, PhD., Selected
Readings in Oral and Maxillofacial
Surgery Vol. 14, #1, 2006.
Injection Injury to the Third Branch of the
Trigeminal Nerve. John R. Zuniga,
DMD, PhD and Derek J. Miller, DDS,
Selected Readings in Oral and Maxillofacial Surgery Vol. 20, #4, 2012.
VOLUME 22.2
SELECTED READINGS
IN
ORAL AND
MAXILLOFACIAL SURGERY
PUBLISHER
SELECTED READINGS IN ORAL AND MAXILLOFACIAL SURGERY
c/o Elizabeth Muscatell
5323 Harry Hines Blvd., M/C 9109
Dallas, TX 75390-9109
PHONE: 214/648-3554 FAX: 214/648-2918
Email to: [email protected]
WEB PAGE: http://www.selectedreadingsoms.com
STAFF
DOUGLAS P. SINN, D.D.S.
EDITOR-IN-CHIEF
CO-FOUNDING EDITOR
FELICE S. O’RYAN, D.D.S.
CO-FOUNDING EDITOR
JAMES E. BERTZ, D.D.S., M.D.
ASSOCIATE EDITOR
THOMAS W. BRAUN, D.M.D., Ph.D.
ASSOCIATE EDITOR
G. E. GHALI, D.D.S., M.D.
ASSOCIATE EDITOR
EDWARD ELLIS, III, D.D.S., M.S.
ASSOCIATE EDITOR
JOHN P. W. KELLY, D.M.D., M.D.
ASSOCIATE EDITOR
THOMAS P. WILLIAMS, D.D.S.
ASSOCIATE EDITOR
GAYLORD S. THROCKMORTON, Ph.D.
MEDICAL EDITOR
ELIZABETH MUSCATELL
ADMINISTRATIVE COORDINATOR
SUBSCRIPTIONS
Order Online at www.selectedreadingsoms.com
Order Online at www.selectedreadingsoms.com
Digital Subscription 2013 $160; Resident Digital Subscription $99*
Digital Subscriptions include online access to the current volume (Vol. 21) and Volumes 10 -20,
with access to full text and PDF issues.
PAYABLE TO “SELECTED READINGS IN ORAL AND MAXILLOFACIAL SURGERY
PAYMENTS IN U.S. FUNDS ONLY.
NOTIFY 30 DAYS IN ADVANCE OF ADDRESS CORRECTION.
*To receive the resident rate, please include a letter of resident status from your residency director or appropriate individual on program letterhead (email to [email protected]).
Selected Readings in Oral and Maxillofacial Surgery is partially supported by
ISSN #1044-7032
Biomet Microfixation (Walter Lorenz Surgical), Jacksonville, Florida