Coronectomy for High Risk Third Molars

What to consider when the roots are close to the nerve

You’ve got a lower third molar that needs treatment, and the roots are close to the inferior alveolar nerve. Before you commit to taking the whole tooth out, coronectomy may be worth considering.

The idea is straightforward: remove the crown and intentionally leave the roots. In the right patient, that can reduce nerve risk. You still need to plan for healing, follow-up and the possibility that those roots may need attention later.

What the trial tells you

Leung and Cheung’s 2009 randomized trial looked at teeth with radiographic signs of close proximity to the inferior dental nerve. It included 231 patients and 349 teeth: 171 allocated to coronectomy and 178 to complete removal. The authors reported nerve deficit in nine patients in the removal group versus one in the coronectomy group.

There’s an important detail here. Sixteen planned coronectomies failed and required complete removal. Your patient needs to understand that leaving the roots isn’t always possible, even when that’s the plan.

This older trial supports coronectomy as an option for selected high-risk teeth. It doesn’t tell you that nerve injury is impossible, or that every difficult third molar is a good candidate.

Read Leung and Cheung’s randomized trial

How that fits with the other research

Abu-Mostafa and colleagues’ 2021 systematic review included seven comparative studies. Temporary inferior alveolar nerve injury after successful coronectomy ranged from 0% to 2.2%. None of the included studies reported permanent injury after coronectomy. They also documented root migration.

Those numbers give you context, but they aren’t a personal risk estimate for the patient in your chair. The studies used different methods and follow-up periods. No reported permanent injuries doesn’t mean the risk is zero. And because the review includes earlier trial evidence, you shouldn’t count it as a completely separate confirmation of the randomized trial.

Read the 2021 comparative systematic review

The roots can still need attention years later

Monaco and colleagues’ 2023 prospective study followed patients for ten years. Of the original 94 patients, 48 patients with 60 coronectomies completed that follow-up. Between years five and ten, two patients developed root exposure, diagnosed at years eight or nine. Another patient needed root removal for orthodontic reasons.

Late problems were uncommon in the patients they followed, but losing nearly half the original group limits how confidently you can apply that rate. Early healing can look fine and the roots can still need attention later. Root movement alone doesn’t automatically mean failure; what matters is whether it causes a clinical problem.

Read Monaco and colleagues’ ten-year follow-up

Work through the decision before you operate

First, be clear about why the tooth needs treatment. Roots close to the canal change your risk assessment, but that finding alone isn’t a reason to operate. Royal College of Surgeons of England guidance describes coronectomy as an option when extraction is indicated and nerve risk is high.

Then ask whether those roots are suitable to leave behind. The guidance lists non-vital teeth, caries with potential pulpal involvement, mobility and apical disease among the tooth-related contraindications. Some pathology requires complete removal. Medical factors and whether the patient can return for care also need to be part of your decision.

Take the patient through the alternatives in plain language. Cover possible conversion to complete removal, the remaining nerve risk, infection, root migration or exposure, and possible future surgery. Document that conversation. You’re discussing a way to reduce risk, without promising a complication-free result.

RCS England guidance on coronectomy selection

Know what you’re taking on and when to refer

As a GP, spotting a possible coronectomy candidate is useful even if you won’t be doing the surgery. Refer when the assessment, procedure or management of complications is beyond your training and resources. Include why treatment is needed, your clinical findings and imaging, and your concern about nerve proximity.

Be clear about who’s reviewing healing and documenting the retained roots. Make sure the patient knows how to get reassessed for new pain, swelling, root exposure or altered sensation. The treating clinician should individualize follow-up and imaging using current local guidance.

Keep building your third molar judgment

If you’d like to work further on case selection, when to refer and postoperative care, these are covered in the Oral Surgery Accelerator. Clinical case videos are available inside the course.

Explore the third-molar training

For dental professionals. Apply this information alongside appropriate surgical training and an assessment of the individual patient.