An Impacted Wisdom Tooth Sitting on the Nerve

Quick answer: Some lower wisdom teeth sit directly on the nerve that supplies feeling to the lip and chin. When a scan shows a genuinely high-risk relationship, removing only the crown and leaving the roots — a coronectomy — avoids the main danger while solving the problem.

The call

Netanel, 22, from Beit Shemesh, had had three episodes of infection around a lower left wisdom tooth in eighteen months. It needed to come out; that part was not in question. What he wanted to know was whether it was true, as a friend had told him, that he could end up with a permanently numb lip.

That is a fair question and it deserves a proper answer rather than reassurance.

What we found

The panoramic x-ray showed a horizontally impacted lower left wisdom tooth lying on its side against the second molar. The roots crossed directly over the inferior alveolar canal — the bony tunnel carrying the nerve that supplies sensation to the lower lip, chin and lower teeth on that side.

There were three classic warning signs on the film: the canal appeared to lose its white outline where it crossed the roots, the roots looked darkened at that point, and the canal was deflected slightly around them.

Those signs mean the relationship needs a three-dimensional look, so we took a CBCT scan. It confirmed the worst-case configuration: the canal ran in a groove in the root, with no bone between nerve and tooth.

The numbers are worth stating honestly. In routine lower wisdom tooth extractions, temporary altered sensation of the lip and chin occurs in a small percentage of cases and permanent altered sensation in well under one per cent. Where a scan shows a direct relationship like this, the risk rises substantially — enough to change the plan.

What we did

A coronectomy. We removed the crown of the tooth — the part causing the infections — and deliberately left the root fragments in place, trimmed below the bone level and covered by the gum.

The logic is simple. The infections came from the crown, which was partly through the gum and impossible to clean. The roots, buried in bone and no longer connected to the mouth, are not a source of infection. Leaving them means never touching the nerve.

The procedure took about forty minutes under local anaesthetic. We were careful not to mobilise the roots at all, since a root that starts to move must then be removed, which reintroduces the risk we were avoiding.

We explained the trade-offs beforehand: bone grows over the retained roots in most cases; the roots sometimes migrate upwards over the following years, away from the nerve, and can then be removed easily if they ever cause trouble; and a small proportion of cases need a second procedure.

The outcome

Healed uneventfully. Normal sensation throughout — no numbness at any stage. At the two-year review the roots had migrated about 3mm away from the canal and bone had filled in above them. No further infections.

What to do if this happens to you

1. Ask to see the x-ray and ask whether the roots are close to the nerve.
2. Ask whether a CBCT scan is warranted if the panoramic film shows warning signs.
3. Ask specifically about the numbness risk in your case — not the general figure.
4. Ask whether coronectomy is an option if the risk is high.
5. Report any numbness that persists beyond the anaesthetic promptly. Early review matters.
6. Do not have wisdom teeth removed without a reason. Symptom-free, cleanable ones can be left and watched.

Wisdom teeth that need assessing? Ramat Beit Shemesh Urgent Dental Care scans before operating when the nerve is close. 055-985-8845 · WhatsApp https://wa.me/972559858845 · Harav Kook 28/1, Beit Shemesh.

Based on real cases treated at the clinic. Names have been changed.