A coronectomy is a specialized dental procedure, an alternative to complete wisdom tooth removal (third molar extraction). It involves removing only the crown (the visible part of the tooth above the gumline) while leaving the roots within the jawbone. This method aims to preserve nearby nerves and reduce complications from full tooth extraction.
When a Coronectomy is Performed
A coronectomy is performed when the roots of a lower wisdom tooth are positioned very close to the inferior alveolar nerve (IAN). This nerve provides sensation to the lower lip, chin, and some teeth. Full extraction in such cases carries a significant risk of nerve damage, which could lead to temporary or even permanent numbness, tingling, or altered sensation in these areas.
To assess root-nerve proximity, dental professionals use 3D cone-beam computed tomography (CBCT) scans. Radiographic signs, including darkening or narrowing of the root, root deflection, diversion or narrowing of the IAN canal, or interruption of the white line of the IAN canal, indicate a heightened risk of nerve injury during a full extraction. The tooth and its roots must also be healthy, free from decay, infection, or excessive mobility, to be suitable for a coronectomy.
The Coronectomy Procedure
The coronectomy procedure typically begins with local anesthesia to numb the surgical area. Intravenous sedation or general anesthesia may also be used. Once the area is numb, a small incision is made in the gum tissue to expose the impacted wisdom tooth. Bone surrounding the crown of the tooth is gently drilled away for access.
The crown is then separated from its roots using specialized instruments and removed. The roots are left undisturbed and smoothed down to lie below the surrounding bone. Finally, the gum tissue is repositioned and stitched closed over the retained roots, often with dissolvable sutures. The procedure usually takes 20 to 40 minutes.
Recovery and Potential Outcomes
Following a coronectomy, patients can expect mild discomfort and swelling, managed with prescribed or over-the-counter pain medication and cold compresses. Soft foods are recommended initially, and physical activity should be limited to support healing. Oral hygiene instructions will be provided, including gentle rinsing with salt water or prescribed mouthwash to minimize infection risk.
The retained roots are expected to remain in the jawbone and may migrate away from the inferior alveolar nerve over time. Root migration, reported in 2% to 85.3% of cases, often happens within 6 to 12 months and is frequently asymptomatic. If roots become symptomatic due to infection, oral cavity exposure, or continued mobility, a second surgical removal might be necessary. This re-operation rate is low (1.8% to 6% of cases), with many secondary removals occurring between 12 and 24 months post-procedure.
Coronectomy has a high success rate (61.7% to 100%), with one study indicating 93%. The procedure significantly reduces nerve injury risk compared to full extraction, with inferior alveolar nerve injury reported between 0% and 9.5%, and lingual nerve injury between 0% and 2%. While immediate complications like pain, swelling, and dry socket (2-12%) can occur, the aim is to prevent long-term nerve damage while allowing retained roots to integrate safely within the bone.