CBCT Before Third Molar Surgery

What will the scan change for this patient

You’re looking at a lower third molar, and the roots look close to the canal on the panoramic image. It’s understandable to want a CBCT before going any further. But before you order it, work out what you need it to tell you and what you’ll do with the answer. More detail doesn’t automatically mean fewer nerve injuries.

What happened when researchers tested it

In a 2015 multicentre randomized trial, Ghaeminia and colleagues studied adults whose panoramic images suggested increased inferior alveolar nerve risk. They analyzed 268 patients with 320 mandibular third molars. One group had an additional CBCT before surgery; the other had no additional imaging.

The main outcome was patient-reported altered sensation one week after surgery. Adding CBCT didn’t produce a statistically significant reduction in temporary nerve injury. The researchers also found no significant differences in the other measured outcomes, including long-term injury.

That matters because they were looking at what happened to patients, not just how clearly you could see the anatomy. It doesn’t prove that CBCT never helps an individual patient, or that the two imaging strategies are exactly equivalent. It does give you a reason to question the idea that getting a scan makes the case safer by itself.

Ghaeminia et al. 2015 • Randomized controlled trial

It wasn’t just one trial

Robbins and colleagues’ 2022 systematic review looked at seven randomized trials comparing additional CBCT with panoramic imaging alone. One reported significantly fewer nerve injuries with CBCT; six didn’t. The authors rated the overall evidence moderate quality and concluded that CBCT doesn’t routinely translate into fewer nerve injuries.

The Ghaeminia trial was included, so don’t count these as separate groups of patients and add them together. The studies also differed in how they defined risk, and there were concerns about bias. The useful takeaway is to be selective about imaging, rather than tell a patient that a scan will prevent a sensory disturbance.

Robbins et al. 2022 • Systematic review

Sometimes it changes what you plan to do

Matzen and colleagues’ 2013 treatment-planning study looked at 186 mandibular third molars. Clinicians first made a plan using panoramic imaging plus stereo-scanography, then reconsidered after seeing the CBCT. The choice between full removal and coronectomy changed for 22 teeth, or 12%.

You can see why that extra information might be useful in a selected case. Just keep the result in perspective. This wasn’t a randomized trial showing fewer nerve injuries. Every tooth received CBCT, and the starting images included stereo-scanography, not simply a routine panoramic image. Changing the plan doesn’t, by itself, prove that the outcome is safer.

Matzen et al. 2013 • Treatment-planning study

Work out your question before ordering

The EADMFR’s 2019 position paper advises against routine CBCT before third-molar removal. It recommends using it for a specific clinical question that conventional imaging can’t answer, while considering the extra radiation exposure and cost. You still need to follow current local imaging requirements.

EADMFR position paper • Imaging guidance

Before requesting a scan, work through these questions:

• What’s still unclear after examining the patient and reviewing the appropriate conventional images?
• Would the answer change the procedure, prompt specialist assessment, or change how you discuss the options with your patient?
• What will you do if the relationship looks closer than expected? And if it looks more reassuring, is this still a case you’re comfortable and competent to manage?

These are practical questions to help you apply selective imaging, not a validated prediction rule. If you already know the patient needs a referral, consider discussing imaging with the receiving clinician before arranging another examination.

Be clear with your patient

Explain what you’re trying to clarify and that nerve injury is still possible. A reassuring image doesn’t replace clinical judgment, sensible case selection or a realistic discussion of alternatives. If you’re considering coronectomy, you’ll need to assess its suitability and follow-up requirements separately.

Try this on your next imaging request

Write one sentence: “The clinical question is ___, and the answer may change ___.” If you can’t fill in both blanks clearly, take a step back and reconsider whether you need the additional imaging.

For more on third-molar assessment, case selection and knowing when to refer, have a look at the Oral Surgery Accelerator’s third-molar training.

Explore third-molar training

For dental professionals. Educational discussion, not a substitute for individualized assessment or local imaging guidance.