The lower jaw nerve and All-on-6: understanding the numbness risk

Where the nerve runs

On each side of the lower jaw, a nerve called the inferior alveolar nerve enters the bone near the back, runs forward through a channel called the mandibular canal, and comes out through a small hole on the outside of the jaw below the premolar teeth, roughly beneath the corners of the mouth. That exit point is called the mental foramen. From there, the mental nerve spreads into the lower lip and chin.

The nerve carries feeling, not movement. It tells you when your lip is touched, when a drink is hot and when food is on your chin. Damage to it does not paralyse the lip, but it can make the lip and chin feel numb, tingly or, occasionally, painful.

Why it matters for All-on-6

In the lower jaw, the space between the two exit points of the nerve, roughly the area from one premolar to the other, has no major nerve running through the bone. That is why the front of the lower jaw is a common place for implants. Behind the exit points, the nerve runs through the bone, and the height of bone above it limits how long an implant can be.

In All-on-6, six implants are spread along the lower jaw. The back implants on each side need to sit either in front of the exit point, above the canal with a safe distance, or tilted to avoid it. As the jaw shrinks after years without teeth, the canal can end up closer to the top of the bone, which makes planning more delicate.

What the research shows

A 2025 systematic review and meta-analysis from Harvard School of Dental Medicine looked at how the distance between the implant and the mandibular canal related to altered sensation. Its findings were striking:

The authors concluded that a distance of 1 mm from the canal might be safe, that implants closer than 1 mm were associated with altered sensation, and that careful planning with 3D imaging is essential. A separate meta-analysis on guided surgery recommends a safety margin of at least 2 mm, because guided placement deviates from the plan by an average of about 1.2 to 1.4 mm. Taken together, the message is that a few millimetres make all the difference.

How surgeons protect the nerve

• A CBCT 3D scan to trace the canal and find the exit points on both sides.
• Choosing implant length and position with a safety margin above the canal.
• Tilting the back implants forward, in front of the exit point, where bone height behind it is limited.
• Surgical guides in some cases. See guided surgery.
• Careful technique, including drill depth control and, sometimes, exposing the exit point to see it directly.

When bone above the nerve is very limited, options include shorter implants, implants only in the front, All-on-4 with tilted back implants, or bone grafting. These trade-offs are discussed on All-on-6 and the alternatives and on our sister guide allon4vsallon6.co.uk.

What you might notice after surgery

After lower jaw surgery, local anaesthetic makes the lip, chin and tongue numb for several hours. That is expected. Swelling can also cause a temporary feeling of fullness or slight change in sensation for a day or two.

• Numbness of the lip or chin that is still present the next morning, well after the anaesthetic should have worn off.
• Tingling, pins and needles, burning or electric-shock sensations in the lip or chin.
• Numbness on one side only that does not improve as swelling goes down.

Report any of these to your surgeon the same day. Early assessment, sometimes with an X-ray or scan, allows the surgeon to decide whether an implant should be adjusted or removed, which can improve the chances of recovery.

Recovery of sensation

Altered sensation often improves over weeks to months, particularly when the nerve was bruised or stretched rather than cut, and when the cause is addressed promptly. A minority of cases are long-lasting. While sensation is reduced, take care with hot drinks, which you may not feel, and check your lip and chin in a mirror after eating.

Consent and honesty

The British Society of Periodontology notes that your dentist should explain the process, risks and benefits before treatment. Nerve injury is a recognised risk of lower jaw implant surgery and should be part of that conversation. A 2022 French study of liability claims found nerve injury after implants was a recurring cause of legal disputes, which highlights the importance of good planning and clear communication. A surgeon who shows you the nerve on your scan and explains how far your implants will be from it is doing exactly what you should hope for.

Questions to ask

• Can you show me where my nerve runs on the scan?
• How far will my back implants be from the nerve canal?
• Will any implants be tilted to avoid it?
• What should I do if my lip is still numb the next morning?
• If there were a problem, how quickly could you see me?

More about risks in general is on risks and complications, and about the day itself on surgery day.

Why the lower jaw is often a good place for implants

It is worth balancing the nerve risk with some reassurance. The front part of the lower jaw, between the two exit points of the nerve, often has dense bone and no major nerve inside it. That is one reason lower-jaw full-arch treatment has a long and successful history. In many people, four or more implants fit comfortably in that front region, and the back implants of an All-on-6 can be positioned or angled so that they stay clear of the nerve. The risk is real but manageable with good planning.

Other structures in the lower jaw

The nerve is the main concern, but there are others the surgeon considers. Near the exit point, the nerve sometimes loops forward inside the bone before it emerges, which the scan should show. On the inside of the front of the jaw there are small blood vessels; the surgeon avoids drilling through the inner wall of the bone. The tongue and floor of the mouth are protected during surgery. A careful 3D plan accounts for all of these.

Bone shrinkage and the nerve

After years of wearing a lower denture, the jaw can shrink significantly. In some people, the nerve canal ends up close to the top of the ridge, and the exit point can be near the surface, where a denture presses on it. That is one reason some long-term denture wearers have tingling or discomfort under the denture. Implants placed with a fixed bridge take the pressure off the gum, which can help. But it also means less bone to work with, so planning is especially important.

What to expect at the follow-up

At your check-up a few days after lower jaw surgery, the dentist may ask whether your lip and chin feel normal on both sides. This is routine. If you notice any difference, say so even if it seems minor; it is useful information to have recorded early.

Common questions

Is numbness normal after lower implant surgery?

Numbness from the local anaesthetic is normal and wears off within hours. Numbness, tingling or burning of the lip or chin that lasts beyond the next morning is not expected and should be reported to your surgeon promptly.

How do surgeons avoid the nerve?

By locating it on a 3D CBCT scan, choosing implant positions and lengths that keep a safety margin, and sometimes tilting implants or using a surgical guide. In All-on-6, the implants towards the back of the lower jaw are placed in front of where the nerve exits the bone.

Is nerve damage permanent?

Often altered sensation improves over weeks to months, particularly if the cause is dealt with quickly. In a minority of cases it is permanent. Early assessment improves the chances.

Does nerve injury affect movement of the lip?

No. This nerve carries feeling, not movement. People with altered sensation can still move their lips normally, though eating and speaking may feel strange.

Is the upper jaw at risk of nerve injury too?

The main concern in the upper jaw is the sinus rather than a major nerve. See our article on the upper jaw and the sinus.

Sources

1. Peña-Cardelles et al. (2025), Med Oral Patol Oral Cir Bucal — Inferior alveolar nerve damage related to dental implant placement: systematic review and meta-analysis
2. Tahmaseb et al. (2018), Clin Oral Implants Res — Accuracy of static computer-aided implant surgery (2 mm safety margin)
3. British Society of Periodontology — Patient FAQs: dental implants (assessment and consent)
4. Inferior alveolar nerve injury following implant placement: medicolegal analysis (2022), J Stomatol Oral Maxillofac Surg

Checked October 2026. Where we give our own view as a clinic, we say so.