What impaction means
Most adults have four wisdom teeth, one at the back of each side of the upper and lower jaw, though some people have fewer or none. They usually come through in the late teens or early twenties. If the jaw has no room for them, they may come through only partly, or not at all.
An impacted tooth is described by the way it lies in relation to the tooth in front of it. Lower wisdom teeth are the ones most often impacted.
Four ways a lower wisdom tooth can be impacted
- Mesioangular. Tilted forwards, towards the tooth in front. The most common kind.
- Vertical. Upright, but held below the level of the bone.
- Horizontal. Lying on its side, crown pointing at the tooth in front.
- Distoangular. Tilted backwards, away from the tooth in front.
Simplified drawing, not to scale.
What it can cause
Many impacted wisdom teeth never cause trouble. Others can lead to:
- pericoronitis, an infection of the gum flap over a tooth that is partly through;
- decay in the wisdom tooth or in the back of the tooth in front, where food gets trapped;
- gum disease around the back teeth;
- less often, a cyst around the buried tooth, or damage to the root of the neighbouring tooth.
Signs include pain or swelling at the back of the jaw, a bad taste, difficulty opening the mouth and a swollen cheek. Swelling that spreads, a high temperature, or difficulty swallowing or breathing needs urgent care: in the UAE, call 998.
When removal is considered
In the UK, the National Institute for Health and Care Excellence (NICE) advises that impacted wisdom teeth with no sign of disease should not be removed routinely. Removal is advised where there is disease, for example:
- decay in the wisdom tooth that cannot be restored;
- infection of the pulp or around the root tip, an abscess or a spreading infection;
- repeated or severe pericoronitis;
- a cyst or tumour around the tooth;
- damage to the wisdom tooth or to the tooth in front, including decay or resorption of its root;
- a tooth in the way of other planned treatment, such as jaw surgery.
A wisdom tooth that is not causing problems is usually monitored at routine check‑ups.
How removal usually proceeds
Assessment. An X-ray, often a panoramic one and sometimes a three‑dimensional scan, shows the position of the tooth, its roots and its relation to the nerve that runs through the lower jaw.
Anaesthesia. Usually a local anaesthetic. Sedation or a general anaesthetic is used in some cases.
Removal. For an impacted tooth, a small cut is made in the gum. Some bone may be removed, and the tooth may be divided into pieces to take it out with less force. Stitches may be placed.
Aftercare. Swelling, stiffness of the jaw and discomfort are common afterwards and settle as the area heals. The dentist gives written aftercare instructions, including what to eat, how to keep the area clean and which signs to report.
Risks
- Dry socket: the blood clot is lost from the socket, leaving painful exposed bone. More likely in smokers and after lower wisdom teeth are removed.
- Infection and bleeding.
- Nerve injury: numbness or tingling of the lower lip, chin or tongue. It is usually temporary, but occasionally long-lasting.
- Damage to nearby teeth or fillings, and, for upper wisdom teeth, an opening into the sinus.
Keeping the back teeth clean matters whether or not a wisdom tooth is removed: see gum disease for daily care that protects them.
Questions patients ask
Should all wisdom teeth be taken out?
No. Guidance from NICE in the UK advises against removing impacted wisdom teeth that show no disease simply to prevent future problems. A wisdom tooth that causes no trouble is usually watched at check‑ups instead.
Why do wisdom teeth get stuck?
They are usually the last teeth to come through, and by then there is often not enough room at the back of the jaw. The tooth may then be blocked by the tooth in front, by bone or by gum.
What is pericoronitis?
An infection of the gum flap that partly covers a wisdom tooth that has only half come through. Food and bacteria collect under the flap, and the gum becomes sore and swollen. A single mild episode is not usually, on its own, a reason for removal; repeated or severe episodes can be.
What is a dry socket?
After an extraction, a blood clot normally fills the socket. If it breaks down or is lost, the bone underneath is exposed and a deep, throbbing pain can develop. It is more common after lower wisdom teeth are removed and in people who smoke. It needs a review by the dentist.
Can an impacted wisdom tooth harm the tooth in front?
Sometimes. Food can become trapped between the two teeth and lead to decay or gum disease on the back of the tooth in front, and occasionally an impacted tooth wears away part of its neighbour's root.
What this page rests on
This page rests on a national clinical guideline (NICE TA1) for when removal is advised, and on published patient guidance for the rest. It is general information: whether a particular wisdom tooth needs treatment can only be decided at an examination with X-rays.
General health information, not a diagnosis or a treatment recommendation for any individual.
Sources
- NICE — Guidance on the extraction of wisdom teeth (Technology appraisal guidance TA1)
- NHS — Wisdom tooth removal
- Oral Health Foundation — Wisdom teeth
- American Dental Association, MouthHealthy — Wisdom teeth