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Leaving a Root Behind on Purpose- Coronectomy

August 26, 2022 11:30 am Published by

by Dr. Karl Koerner

Recently, I was working for the first time in a clinic for low income patients and helping a 32 year old man with mild pericoronitis from an impacted third molar.  The extraction commenced routinely with the flap, bone removal and crown removal.  Sectioning and removing the mesial and distal roots did not go as planned.

impacted third molar extraction coronectomy

After removing parts of roots, I realized they were anchored and not going to come out.  If I continued to use my bur deeper, I would increase the chance for disaster, and cause injury or damage to the IAN.  I opted to proceed with coronectomy in order to prevent likely nerve damage.

Using a #8 round bur, I smoothed off the remaining root for a flat (albeit a little curved), clean, smooth appearance on the root and I let it stay.  (insert pic of post op xray)

The rules for coronectomy were presented in Monaco’s 2012 JADA article:  Coronectomy: A surgical option for impacted third molars in close proximity to the inferior alveolar nerve.impacted third molar after coronectomy

The article mentions 43 cases of coronectomy with no failures.  A failed coronectomy would be one with postoperative infection or on-going pain. The rationale on how it works were provided in Nishimoto’s 2020 JOMS article.  The procedure requires sterile saline irrigation, meticulous pathology debridement, cutting at least 3-4 mm apical to the bone crest for a sterile clot “pulp cap”, no enamel left behind, antibiotics and primary closure.  Primary closure is not usually being the norm for garden variety lower impactions (Danda’s 2012 JOMS article).  In this case, in accordance with protocol, the exposed second molar root surface was detoxified so that bone could adhere to it (mechanically with curettage and chemically with a solution to condition the root surface).

Monaco’s article concluded that coronectomy is a safer alternative to complete extraction when the third molar is in close proximity to the mandibular canal.  After coronectomy, root migration was highest during the first three months, with no further migration observed after 12 months. Root migration was asymptomatic, and in once case, the roots were removed months later.  In this case, risk of neurological injury was significantly reduced die to the migration of the roots.

impacted third molar course for dentistsWhen it comes to third molar extraction, using all the tools in your arsenal to achieve the best possible outcome for the patient is important.  Performing coronectomy correctly and successfully is a treatment option that is proven to be safe, effective and minimizes the risk of nerve injury.  Our Continuum 4: Impacted Third Molars Course covers the techniques and protocols for successful coronectomy in addition to instruction on complete removal of impacted third molars.  Learn more about Continuum 4 here.


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