A coronectomy is a specialized dental surgical procedure involving the removal of a tooth’s crown while deliberately leaving the roots undisturbed within the jawbone. This technique is primarily used as an alternative to complete tooth extraction, most often for impacted lower wisdom teeth (mandibular third molars). The purpose of this approach is to mitigate a specific risk associated with traditional extraction. By removing only the top portion, the procedure prioritizes the preservation of nearby anatomical structures when full removal presents a danger to the patient’s long-term sensory function.
Clinical Rationale and Indications
The primary reason a coronectomy is chosen over a full extraction is the close anatomical relationship between the tooth roots and the inferior alveolar nerve (IAN). This major nerve runs through the lower jawbone, providing sensation to the lower lip and chin. When a wisdom tooth is deeply impacted, its roots may be wrapped around the nerve canal, making traditional extraction a high-risk procedure for causing permanent nerve damage. Radiographic signs, such as the darkening of the tooth root where it crosses the nerve canal, indicate a heightened risk of injury to the IAN during full removal. Damage to this nerve can result in paresthesia, a persistent numbness or tingling sensation in the lip and chin area. Coronectomy is indicated in these high-risk scenarios, as leaving the root fragments in place shields the nerve from the mechanical trauma of extraction forces.
A patient is not a candidate for a coronectomy if the tooth or roots are infected, decayed, or if there is significant disease around the root tips. The roots must be healthy and non-mobile for the procedure to be considered, as leaving diseased tissue behind leads to further complications. If the roots are loose or mobile during the procedure, the surgeon must convert the coronectomy into a full extraction.
The Surgical Procedure
The coronectomy procedure begins with the administration of local anesthesia to completely numb the surgical site, though sedation or general anesthesia can also be used for patient comfort. The surgeon then makes a precise incision in the gum tissue, creating a flap to expose the impacted wisdom tooth and surrounding bone. A small amount of bone tissue overlaying the crown may be gently removed with a surgical drill to ensure clear access.
Next, the crown is carefully separated from the roots using a high-speed surgical burr and specialized instruments. This separation is performed below the crest of the alveolar ridge (the surrounding jawbone). The crown is then safely removed, ensuring the remaining roots are not disturbed or mobilized during this process.
A critical step involves ensuring all coronal pulp tissue is removed from the root canal entrances. The remaining root surface is smoothed and trimmed to a level at least three to four millimeters below the bone surface. This depth is crucial for encouraging the overlying soft tissue to heal and cover the root. Finally, the gum flap is repositioned back over the retained roots, and the surgical site is closed with stitches, often using resorbable sutures.
Recovery and Long-Term Monitoring
Patients experience less post-operative pain and swelling following a coronectomy compared to a full surgical extraction, but recovery is still necessary. Discomfort is managed with pain medication, and antibiotics may be prescribed to minimize infection risk. For the initial days, patients are advised to adhere to a soft or liquid diet and maintain meticulous oral hygiene, often including a medicated mouthwash.
Short-term complications can occur, including localized infection or inflammation. The risk of dry socket is lower than with a complete extraction because the root fragments remain covered by a blood clot. Swelling and limited mouth opening (trismus) are common side effects that resolve within the first two weeks.
Long-term care involves periodic follow-up appointments to monitor the retained root fragments using dental X-rays, typically taken at six months, one year, and two years post-surgery. This monitoring checks for signs of infection or changes in the root fragments’ position. In approximately 15% of cases, the roots may naturally migrate away from the nerve over time. If this root migration occurs, it may necessitate a simple, subsequent removal, but the roots are then in a safer position for extraction without the original risk of nerve damage.