Coronectomy a Cognizance Technique Nescient to Oral Surgeons

JDSOR
REVIEW ARTICLE
10.5005/jp-journals-10039-1015
Coronectomy a Cognizance Technique Nescient to Oral
Surgeons: Translational Paradigms
Coronectomy a Cognizance Technique Nescient to
Oral Surgeons: Translational Paradigms
1
Anand Kumar, 2Ram Kumar Srivastava, 3Iqbal Ali, 4Puneet Wadhawani, 5Ruchika Khanna
ABSTRACT
Coronectomy (intentional partial tooth removal) is a new method
introduced in oral and maxillofacial surgery for the elimi­nation
of the crown of mandibular third molar. Resear­chers have sta­
ted that the usual persistent accusations among patients with
emble­matic third molars are pain, swelling, food impaction and
puru­lent discharge. Impacted mandibular third molars also
have been displayed negatively to ligament; root resorp­tion
can lead to increased pocket depth merged with the damage
of attachment. Injury to the inferior alveolar nerve fiber (IAN)
during the wrenching of impacted mandibular third molars in
vicinity to the mandibular canal is a postoperative dilemma that
most often occurs. Surprisingly seldom research is going with
this process, and all investigations are achieving the same that
this process has no harm with the patients as well-economically
frugal procedure but still this procedure is not in utilizing as well
as no further or very fewer research are going with this process.
Keywords: Coronectomy, Deliberate vital root retention, Partial
root removal, Partial odontectomy.
How to cite this article: Kumar A, Srivastava RK, Ali I,
Wadhawani P, Khanna R. Coronectomy a Cognizance Tech­
nique Nescient to Oral Surgeons: Translational Paradigms. J
Dent Sci Oral Rehab 2014;5(2):65-69.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
A coronectomy or prejudiced odontectomy (American
Dental Association-D7251) is a process employed to extract
a tooth that has not still broken through the surface of the
gum, but has an enhanced possibility of injuring the nerve
that equips sensation to the lower lip and chin. The process
is accomplished by passing the surrounding gingiva away
from the mandibular third molar tooth and then sectioning
the crown (top) off the root of the tooth. The patients with
higher risk of experiencing inferior alveolar never injury
1
Assistant Professor, 2-4Professor, 5Senior Resident
1-4
Department of Oral and Maxillofacial Surgery, Career Post
Graduate Institute of Dental Sciences, Lucknow, Uttar Pradesh
India
5
Department of Oral Medicine and Radiology, Career Post Graduate
Institute of Dental Sciences, Lucknow, Uttar Pradesh, India
Corresponding Author: Anand Kumar, Assistant Professor
Department of Oral and Maxillofacial Surgery, Career Post Graduate
Institute of Dental Sciences, Lucknow, Uttar Pradesh-226016, India
Phone: 09621848802, e-mail: anandkmr901@gmail.com
due to removal of impacted mandibular third molar, does
coro­­nectomy decreases the risk of nerve injury or other postoperative complications such as temporary loss of sensation,
pain and swelling in correlation with complete elimination of
the impacted mandibular third molar tooth. It is performed
in such a direction so that the enclosing bone will ‘fill in’
the area that was owned by the crown of the tooth. The roots
of the mandibular third molar tooth are left in position so
that the possibilities of damaging the nerve that give sensation
to the lower lip and chin are reduced. It reduces morbidity of
the nerve after the operation on high-risk mandibular third
molars. Coronectomy or intentional partial odontectomy is
a technique by means of which the roots of the mandi­bular
third molar tooth that is viewed nearby to the inferior alveolar
canal on diagnostic radiographic imaging is left in situ. The
procedure was first described by Knutsson et al in 1989 but
was not popularized due to the reported complications of root
exposure and infection from the procedure.1
Coronectomy is an almost innovative method and to date
there have solely done a small quantity of publications that
review its’ effectiveness as a treatment modality. Damage to
the inferior alveolar nerve fiber (IAN) during surgical extraction of deeply impacted mandibular third molar (wisdom)
teeth is a well-kenned complication. Over the ages, opinions
of IAN debt after impacted mandibular third molar teeth
surgery were reported from 0.4 to 8.4%. Damage to IAN can
be impute to compression of the nerve either by indirect force
given by the root during extraction, vigorous elevation or
instantly by elevators. If the impacted mandibular third molar
feels the necessity for extraction is in close contiguity to the
IAN, then traditionally panoramic radiography has been a
pillar for evaluation. Impacted mandibular third molar teeth
are in proximity to the lingual, inferior alveolar, mylohyoid
and buccal nerves.2 Coronectomy procedure involves using
the buccal approach by conventional bur method followed
by removal (guttering) of buccal bone using a fissure bur
down to the amelodentinal junction (crown root junction).
The mandibular third molar is the tooth which is mostly
affected, but seldom can the second molar and even the first
molar roots be in intimate analogy to the inferior alveolar
nerve. The procedure of coronectomy (Flow Chart 1), or
deliberate vital root retention, has been proposed as a method
of separating the crown of an impacted mandibular third
Journal of Dental Sciences and Oral Rehabilitation, April-June 2014;5(2):65-69
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Anand Kumar et al
Flow Chart 1: Steps to plan a coronectomy
molar tooth but leaving the roots, which may be intimately
related with the inferior alveolar nerve, untouched so that
the possibility of nerve damage is reduced.3
If the mandibular third molar is in a horizontal manner,
it is requisite to accomplish major bony surgery to concep­
tualize the crown that is sectioned in a buccolingual way
and in a mesiodistal direction. In this case, the crown part is
kindred to the decorum assumed for whole mandibular third
molar removal. In cases of root mobilization, during crown
sectioning, the root should be extracted because the mobility
of third molar can facilely lead to disease of the alveolus.
Root migration may withal effect the eruption of the root
fragments in the oral cavity and in the future late migra­
tion of the root fragment may befall in some cases, but is
capricious. In these cases, the extraction is uncomplicated
because there is no proximity to the inferior alveolar nerve
and the roots are mobile. However, in each circumstance the
root fragments move into a secured position with respect
to the inferior alveolar nerve, and it can be visualized that
should extraction become compulsory the nerve would not
later be at high risk.4 Case reports have suggested that it take
up to 10 years for the root fragments to erupt.5
Flap Design (Reframing)
When a tooth is partially impacted, in order to obtain primary
closure of the wound it is advisable to perform a triangular
flap with a mesial releasing incision distal to the second molar.
In this circumstance, the releasing incision is not repo­si­­tioned,
and the flap is sutured to the lingual side to obtain the closure.
66
In the case of a completely impacted mandi­bular third molar,
it is easier to obtain a primary wound closure because there
is sufficient gingival tissue, and the maxillo­facial surgeon
can choose either a triangular or envelope flap by modified
wards incision.
The drawbacks of this procedure involve deep periodontal
pockets on the distal of the second molars (relative to those
after extractions incommensurable circumstances), root mig­
ration with the possible desideratum of a second pro­cedure,
dry sockets, local postoperative infections, post­operative
pain and inadvertent root extraction, or root walk-out during
surgery which may increase the jeopardy of IANI (withal
enclo­­sure as a failed coronectomy).6-8
Coronectomy of lower third molars is NOT carried out
in the following conditions.9
• Impacted mandibular third molar tooth roots are not
encountering the IAN canal.
• Mandibular third molar tooth with either existing root
apex or crown infection.
• Pre-existing anesthesia of the IAN.
• Pre-existing mobility of the tooth as any retained roots
may serve as a movable foreign body and develop into
a nidus for infection/migration.
• Mandibular lower third molar that are horizontally
impac­ted along the path of the Inferior alveolar nerve as
sectioning the tooth crown could compromise the IAN.
• Systemic condition makes susceptible to local infection
such as diabetes, AIDS and simultaneous chemotherapy
and Local factors involve metabolic bone diseases (e.g.
fibrous dysplasia), history of radiotherapy to the mandible.
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Coronectomy a Cognizance Technique Nescient to Oral Surgeons: Translational Paradigms
MODERN THOUGHT IN CORONECTOMY
Two types of coronectomy10 method are published recently
are:
1. Modified coronectomy
2. Grafted coronectomy
As with the traditional coronectomy, modified grafted
coro­­nectomy requires the concept of the crown and part of the
roots of an impacted mandibular third molar in situations with
a high risk of inferior alveolar nerve injury. This modified
method proposes steps to limit the dilemma of intraoperative
root loosening. It achieves this by preserving the radicular
remnant during the time of cutting as well as when dis­
severing the coronal section off, thus overall decrementing
the peril of nerve injury. As another modification, to reduce
or prevent periodontal pockets on the distal of the second
molar, the technique calls for the engendering of periodontal
‘scaffolding,’ which is accomplished through grafting, thus
the designation modified and grafted coronectomy.11
DISCUSSION
Evidence suggests that coronectomy is a good option for
patients in jeopardy of experiencing inferior alveolar nerve
injury but is technique sensitive and not without compli­
cation. Coronectomy is a procedure intentionally aiming
to abstract only the crown of an impacted mandibular third
molar, leaving the root undisturbed, and thus evading possible
direct or indirect damage to the IAN. This tech­nique was first
described by Knutsson et al in 1989 in a retro­spective study
of 33 patients. Six more papers about coro­nectomy with 3
case reports and 2 retrospective studies, and one randomized
controlled tribulation by Renton et al in 2005. In this last
study, 128 patients were randomized to undergo either
extraction or coronectomy of sagaciousness teeth.13,14 The
group undergoing extraction was found to be significantly
more prevalent in experiencing IAN deficit after surgery
than the coronectomy group, while no paramount differences
could be concluded in terms of other surgical morbidities.
The other studies additionally drew kindred conclu­sions.
One mundane finding, however, was the slow superficial
migration of the sagaciousness tooth root after coronectomy.
It had been suggested the root is only designated to be
abstracted only if it is exposed intraorally, but the jeopardy
of IAN damage of the second surgery is reduced as the root
has migrated away from the nerve.
Pogrel et al4 evaluated 41 patients who underwent coro­
nectomy on 50 lower third molars, with follow-up of at
least 6 months. This technique was utilized because there
was radiographic evidence of a close relationship between
the roots of the tooth and the inferior alveolar nerve. The
authors reported that there were no cases of inferior alveolar
nerve damage in this study. Preoperative and postoperative
prophylactic antibiotics; one paper suggested postoperative
antibiotics only; another paper suggested no antibiotics were
indispensable; and the other two papers did not mention
antibiotics Pogrel 2004,4 O’Riordan 2004,14 Renton 200415
respectively.
Dr Mike YY Leung and Prof Lim K Cheung18 conducted
a prospective cohort study of 4338 wisdom tooth surgeries
between 1998 and 2005 in the Prince Philip Dental Hospital,
which is by far the largest study reported in the literature.
The prevalence of LN and IDN injuries were 0.69 and 0.35%
respectively.16,17,20
Monaco G21 et al (2012) evaluated the postoperative
compli­cations of 43 coronectomies of impacted mandibular
third molars in 37 patients (17 men and 20 women) and
concluded that Coronectomies are safer to perform than
complete extractions in situations in which the third molar
is in close proximity to the mandibular canal. Root migration
generally is asymptomatic, but in a case in which the patient
underwent a second operation, the risk of the patient’s
experiencing neurological injuries was reduced. The authors
used cone-beam computed tomographic images to determine
that all of the teeth that underwent a coronectomy were in
close proximity to the IAN.19-22
Many studies have reported the frequency of nerve injury
during the removal of third molars (Robinson 1997) and most
indicate that inferior alveolar nerve function is disturbed
after 4 to 5% of procedures (1.3-7.8%).23
Inferior alveolar nerve injury (IANI) was the most
serious complication which occurred during some failed
coro­nectomies, where the remaining root was inadvertently
mobilized during surgery. This mandated the surgeons to
proceed with the extraction of the entire root in 4 to 38%
of the cases.12,14
The clear benefit of a successful coronectomy is the avoi­
dance of IANI. The disadvantages of this technique include
deep periodontal pockets on the distal of the second molars
(similar to those after extractions in comparable circum­
stances), root migration with the possible need of a second
procedure, dry sockets, local postoperative infections, postoperative pain and inadvertent root removal, or root walk-out
during surgery which may increase the risk of IANI (also
known as a failed coronectomy).4,5,22
Rood and Shehab in 1990 suggested diversion of the
canal, darkening of the root and interruption of the white line
of IAN to be significantly related to IAN injury. Sedaghatfar
et al23 in 2005 performed a retrospective cohort study and
confirmed that, and adding to its narrowing of the root to
be an additional significant sign to predict the proximity
of nerve and root. These radiographic signs only indicate
to surgeons and patients that there is an increased risk of
Journal of Dental Sciences and Oral Rehabilitation, April-June 2014;5(2):65-69
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Anand Kumar et al
nerve damage associated with the removal of the corres­
pon­ding wisdom tooth, but not prevention to it if the tooth
is being removed. Coronectomy should be considered as an
alternative for patients who require removal of sympto­matic
mandi­bular third molars and who have an increased risk
of experiencing inferior alveolar nerve injury as assessed
by means of radiography. However, because of potential
compli­cations of the technique and inconsistencies in radio­
graphic interpretation, a qualified surgeon should perform
the procedure.
Hatano et al15 compared coronectomy with traditional
extraction on 220 patients, 118 in the extraction group and
102 in the coronectomy group. The mean follow-up time
was 13 months in the extraction group and 13.5 months in
the coronectomy group. Six inferior alveolar nerve injuries
(5%) were found in the extraction group. In the coronectomy
group, 1 patient (1%) had symptoms of nerve injury.
The peril of such an event is commonly evaluated from
radiographic examination as a component of the treatment
orchestrating appointment. Studies have shown that on a
panoramic radiograph diversion of the inferior dental canal
(IDC), darkening and/or root interruption of the white lines
of the canal, narrowing of the canal, and deflection of the
roots denoted a possible intimate nerve relationship to the
tooth.24
Vinod Patel et al (2013) stated that Coronectomy of
unerup­ted teeth associated with dentigerous cysts is an effec­
tive treatment when there is high risk of injury to the infer­
ior dental nerve injury or potential for mandibular frac­ture.
Further work with larger numbers and longer follow-up is
requi­red to discover the long-term outcome of the electively
retained root.25
Despite these positive reports on coronectomy, this technique is yet to gain popularity because of surgeons’ concerns
about the outcomes and short and long-term compli­cations.
However, outcomes cognate to treatment of neurosensory
perturbance after sagaciousness tooth surgery remain variable, so coronectomy, if proven to be safe, could be utili­
zable in minimizing the occurrence of neurosensory deficit
of sagaciousness teeth that are at high risk of nerve damage.
There are currently no standards regarding the timing and
frequency of follow-up of patients having coro­nectomy.
Most authors take radiographs immediately post-operatively
and 6 months later. Later radiographs are taken if the patient
becomes symptomatic.
CONCLUSION
Coronectomy is a secure alternative to the entire extraction
of impacted mandibular third molars, to reduce neurological
damage risks in cases with radiological diagnosis of inferior
68
alveolar nerve in proximity to the impacted tooth. The
root migration is usually asymptomatic but when a second
surgery is required, the extraction of a root fragment is safer
because of the migration, which results in gaining distance
from the mandibular canal.
Coronectomies are safer to perform than perfect extrac­
tions in situations in which the third molar is in proxi­mity
to the mandibular canal. Root migration and nerve injury
usually is asymptomatic but in a case in which the patient
under­went a second operation, the peril of the patient’s expe­
ri­­­­en­cing neurological injuries may reduce. Neuro­sensory
deficit is a consequential risk in lower sagaciousness tooth
surgery. Due to the anatomical positions, the lingual nerve
(LN) and inferior dental nerve (IDN) are in jeopardy in the
procedure, resulting in tongue numbness with taste pertur­
bing in LN injury, or lower lip numbness in IDN injury on
the affected side.
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