A coronectomy is a specialized dental procedure where the crown, or the visible top part of a tooth, is surgically removed while the roots are intentionally left embedded within the jawbone. This technique is primarily used as an alternative to the complete extraction of an impacted tooth, most commonly the lower wisdom teeth (mandibular third molars). The procedure’s goal is to resolve the problems caused by the tooth’s crown while preserving the tooth roots. By only removing the crown, the oral surgeon avoids disturbing the roots and the surrounding bone structure. This conservative approach is reserved for specific anatomical situations where a traditional extraction presents an elevated risk of complication.
Why Coronectomy is Performed
The decision to perform a coronectomy is directly related to the location of the tooth roots in proximity to the inferior alveolar nerve (IAN). The IAN runs through a canal inside the lower jawbone, providing sensation to the lower lip, chin, and teeth. When a wisdom tooth is impacted, its roots can be positioned extremely close to, or even entwined with, this nerve canal, a condition visible on specialized X-rays or CT scans.
Removing the entire tooth in this scenario carries a significant possibility of damaging the IAN, which could result in paresthesia—a long-term alteration of sensation. This neurological injury can manifest as numbness, tingling, or pain, impacting a person’s quality of life. Coronectomy serves as a risk-reduction strategy, minimizing nerve damage by leaving the root portion undisturbed.
Understanding the Surgical Procedure
The coronectomy procedure begins with the administration of local anesthesia, though some patients may opt for sedation. The oral surgeon makes an incision in the gum tissue, creating a flap to expose the impacted wisdom tooth and the surrounding jawbone. A high-speed dental drill is used to remove a small amount of bone around the crown to access the cementoenamel junction, the boundary between the crown and the root.
Crown Removal
The crown is carefully sectioned and removed using specialized instruments, ensuring no force is applied that might mobilize the remaining roots. After removal, the remaining root surface is smoothed down with the drill to ensure it rests a few millimeters below the surrounding bone level. It is essential that the pulp tissue, which contains the tooth’s nerve and blood vessels, is completely removed from the root canal openings to prevent infection. Finally, the gum flap is repositioned over the retained roots and secured with dissolvable sutures to seal the surgical site.
Immediate Recovery and Follow-Up Care
Patients can expect common post-operative symptoms following a coronectomy, including swelling, mild bleeding, and discomfort, similar to a standard tooth extraction. Pain is managed with prescribed or over-the-counter medication, and swelling is addressed by applying ice packs to the cheek during the first 24 hours. A soft-food diet is recommended initially to prevent trauma to the surgical site. Patients must avoid using straws, which can dislodge the healing blood clot.
Maintaining meticulous oral hygiene is important, including gently brushing around the area and following instructions for salt-water rinses after the first day. Follow-up care involves mandatory radiographic imaging, typically at three, six, and twelve months post-surgery. These X-rays monitor the retained roots, checking for stability and confirming that the roots are not showing signs of infection or migration.
Long-Term Prognosis and Risks
The long-term goal of a successful coronectomy is for the retained root fragments to become completely covered by new bone, a process known as root submergence. Over time, the roots often migrate slowly upward or forward, moving away from the inferior alveolar nerve. This migration further reduces the long-term risk of nerve damage. The procedure has a high success rate in preventing IAN injury, with nerve deficit reported as extremely low in high-risk cases.
Potential Complications
Despite its benefits, a coronectomy carries a small risk of long-term complications, most notably infection of the retained roots or root exposure through the gum tissue. If the retained roots become infected or migrate significantly enough to be exposed, they must be surgically removed in a secondary procedure. Because the roots have usually moved away from the nerve by this point, the subsequent extraction is often less complicated and carries a much lower risk of nerve injury than a full initial extraction. The need for this second surgery occurs in a small percentage of cases, typically around 5% to 15% over several years.