Exodontia.Info
Coronectomy /
Intentional Partial Odontectomy
Coronectomy is the removal of the crown of a
tooth, leaving the roots
in situ.

When applied to a lower wisdom tooth or any lower un-
erupted posterior tooth, it is a measure adopted to avoid
damage to the
Inferior Alveolar Nerve (IAN) (the nerve that
supplies feeling / sensation to the lip and chin) when the X-
ray has suggested an intimate relationship between the
roots of the lower wisdom tooth and the
IAN and the tooth
still needed to be removed.

The expectation after removing the top of the tooth is that
the roots will remain in place and eventually cover with
bone.

Roots encased in bone can remain buried in the jaw for
years and rarely cause problems.

Coronectomy of lower molars is NOT carried out in the
following situations
:

  • Wisdom tooth roots are not touching the IAN canal
  • Wisdom tooth with either active root tip or crown
    infection
  • Pre-existing numbness of the IAN
  • Pre-existing mobility of the tooth as any retained roots
    may act as a mobile foreign body and become a nidus
    for infection / migration.
  • Teeth that are horizontally impacted along the course
    of the IAN as sectioning the tooth crown could
    endanger the IAN.
  • Systemic condition predisposing to local infection such
    as diabetes, AIDS and concurrent chemotherapy.
  • Local factors predisposing to infection such as
    metabolic bone diseases (e.g. fibrous dysplasia),
    history of radiotherapy to the lower jaw.
This list of warnings might seem excessive to some
however the legal ruling in the case of
Chester vs Afshar
(2004)
would suggest that it is quite prudent / necessary to
list them.  Others might say that there isn't enough
information but where do you stop?

The following list of warnings regarding coronectomy is
neither exhaustive nor is it predictive.  You are to have a
tooth decoronated.

You can expect the following:
Last Updated 3rd July 2013
Coronectomy / Intentional Partial Odontectomy Specific Warnings:

Antibiotics (pre- & post-op).  These are recommended to lower the chance of
infection either in the socket or the tooth pulp.  These will be given at the clinicians’
discretion.

Primary Closure.  The retained roots are covered over by the gum to facilitate
healing of the pulp, socket and to lessen the chance of operation site infection.

Osteo-cementum Growth.  The root margins are trimmed several millimetres
below the crest of the socket to encourage bone &
osteo-cementum formation
over the retained roots, sealing off the roots from the mouth.

Roots inadvertently removed at the time of attempted coronectomy.  When it came
to removing the crown, it was found that the roots as well were mobile.  This
ranges from 3 - 9%.  If the roots are mobile, we are obliged to remove them and
there is obviously the risk to the
IAN (which this procedure was trying to avoid).

Numbness of Chin, Lip ± Tongue.  The Inferior Alveolar & Lingual Nerves may still
be damaged during the procedure resulting in numbness affecting the tongue +/-
the chin and lower lip.  The numbness of the tongue seems to be quite short-lived
and has a low incidence.  The numbness of the chin ± lip tended to occur when on
attempting the coronectomy, the roots were found to be mobile and had to be
removed.

Root Migration. Subsequent migration of the roots away from the IAN occurred in
14 - 81% of cases.

Later Removal of Roots.  This can happen in up to a 2 - 6% of cases.  If the roots
irritate overlying tissues or the adjacent tooth or otherwise become symptomatic,
they may need to be removed.  Even though a 2nd surgery would be needed, the
possibility of nerve damage should be negligible since the roots would have
migrated away from its original resting place next to the
IAN.  Since the purpose of
the coronectomy is to avoid this damage, this goal would have been accomplished
even though a 2nd surgical procedure was necessary to remove the remaining
root.


General Surgical Warnings:

Pain.  As it is a surgical procedure, there will be soreness after the tooth removal.  
This can last for several days.  Painkillers such as
ibuprofen, paracetamol,
Solpadeine or Nurofen Plus are very effective.  Obviously, the painkiller you use is
dependent on your medical history & the ease of the operation.

Swelling.  There will be swelling afterwards.  This can last up to a week.  Use of
an icepack or a bag of frozen peas pressed against the cheek adjacent to the
tooth removed will help to decrease the swelling.  Avoidance in the first few hours
post-op, of alcohol, exercise or hot foods / drinks will decrease the degree of
swelling that will develop.

Bruising & Bleeding into Cheeks.  Some people are prone to bruise.  Older
people, people on
aspirin or steroids will also bruise that much more easily.  The
bruising can look quite florid; this will eventually resolve but can take several weeks
(in the worst cases).

Swelling that does not resolve within a few days may be due to bleeding into the
cheek.  The cheek swelling will feel quite firm.  Coupled with this, there may be
limitation to mouth opening and bruising.  Both the swelling, bruising and mouth
opening will resolve with time.

Stitches.  The coronectomy site will often be closed with stitches.  These dissolve
and will ‘fall out’ within 10 – 14 days.

Limited Mouth Opening.  Often the chewing muscles and the jaw joints are sore
after the procedure so that mouth opening can be limited for the next few days.  If
you are unlucky enough to develop an infection afterwards in the socket, this can
make the limited mouth opening worse and last for longer (up to a week or so).

Post-op Infection.  You may develop an infection in the socket after the operation.  
This tends to occur 2 – 4 days later and is characterised by a deep-seated
throbbing pain, bad breath and an unpleasant taste in the mouth.  This infection is
more likely to occur if you are a smoker, are on the contraceptive pill, on drugs
such as steroids and if bone has to be removed to facilitate tooth extraction.

If antibiotics are given, they are likely to react with alcohol and / or the
Contraceptive Pill (that is, the ‘
Pill’ will not be providing protection).

Surrounding Teeth.  The surrounding teeth may be sore after the extraction; they
may even be slightly wobbly but the teeth should settle down with time.  It is
possible that the fillings or crowns of the surrounding teeth may come out, fracture
or become loose.  If this is the case, you will need to go back to your dentist to
have these sorted out.  Every effort will be made to make sure this doesn’t
happen.  In very rare instances, the surrounding teeth may actually come out as
well as the intended tooth.

Failure of Anaesthesia.  In rare cases, the tooth can be difficult to ‘numb up’.  This
can be due to a number of reasons.  The more common ones include inflammation
± infection associated with the tooth, anatomical differences & apprehension.  If
the tooth fails to ‘numb up’ then its removal will be rescheduled with antibiotic cover
or perhaps done under sedation or even a GA.


Useful Articles:

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004.   Coronectomy
(Intentional Partial Odontectomy of Lower Third Molars)

J Oral Maxillofac Surg 2004.  Coronectomy: A Technique to Protect the Inferior
Alveolar Nerve

International Dentistry.  Coronectomy - An Alternative Therapy for the symptomatic
impacted 3rd molar - Report of 9 cases

British J Oral Maxillofac Surg 2006.  Is Coronectomy Really Preferable to
Extraction?

J Oral Maxillofac Surg 2009.  Clinical Evaluations of Coronectomy (Intentional
Partial Odontectomy) for Mandibular Third Molars Using Dental Computed
Tomography - A Case-Control Study

Oral Surgery, Oral Medicine, Oral Pathology,Oral Radiology, and Endodontology
2009.  Safety of coronectomy versus excision of wisdom teeth - a randomized
controlled trial

Oral Surgery 2010.  A Review of Coronectomy

British Dental Journal 2010. Coronectomy – Oral Surgery’s answer to modern-day
conservative dentistry

Dental Update 2010.  Coronectomy of a 3rd Molar with Cyst Lining Enucleation in
the Management of a Dentigerous Cyst

Dental Update 2011.  Coronectomy of Third Molar. A Reduced Risk Technique for
Inferior Alveolar Nerve Damage

JOMS 2011.  Coronectomy in Patients With High Risk of Inferior Alveolar Nerve
Injury Diagnosed by Computed Tomography

BDJ 2012.  Notes on Coronectomy

Dental Update 2013.  To Retrieve or not to Retrieve the Coronectomy Root - The
Clinical Dilemma

Dental Update 2013.  Update on Coronectomy.  A Safer Way to Remove High Risk
Mandibular 3rd Molars