what is an impacted wisdom tooth

"Impacted" simply means stuck. Wisdom teeth are the last teeth to form, usually arriving between the late teens and mid-twenties, and by then the jaw often has no room left. The tooth tries to erupt, meets an obstacle, and stays where it is, fully or partly hidden.

The ways a wisdom tooth can be stuck

Dentists describe impaction by the angle of the tooth and how deep it lies:

• Mesioangular: tilted forward, leaning into the back of the second molar. This is the most common pattern in the lower jaw.
• Horizontal: lying on its side, pushing into the roots of the tooth in front.
• Vertical: upright but blocked, often still under gum or bone.
• Distoangular: tilted backwards, away from the other teeth. This is common in the upper jaw.

Depth matters too. A soft-tissue impaction is covered only by gum. A partial bony impaction is partly covered by bone, and a complete bony impaction is fully buried in the jaw.

Why it happens

The main reason is space. Modern diets are soft, jaws tend to be smaller than the full set of 32 teeth needs, and the wisdom tooth arrives last, when every other tooth has already taken its place. Genetics plays a part: if your parents had impacted wisdom teeth, you are more likely to.

Problems an impacted tooth can cause

• Pericoronitis: infection of the gum flap over a partly erupted tooth. Food and bacteria collect under the flap, causing pain, swelling, bad taste and difficulty opening the mouth. See our page on pericoronitis.
• Decay on the second molar: a tilted wisdom tooth creates a trap that you cannot clean, and the cavity often forms on the valuable tooth in front.
• Bone loss between the two molars.
• Cysts: occasionally a fluid-filled sac forms around a buried tooth and slowly enlarges in the bone.
• Pain that feels like it comes from elsewhere, such as the ear, jaw joint or the teeth in front.

Problems it does not always cause

A completely buried tooth with no symptoms and no changes on X-ray may never cause trouble. Removal is not automatically required; many such teeth are simply monitored. The partly erupted tooth, half in and half out, is the one most likely to cause repeated problems.

How it is diagnosed

Your dentist looks for a swollen flap of gum or a tooth edge peeking through at the very back, and takes a digital X-ray (RVG) to see the angle, roots and the bone around it. When a lower tooth seems close to the nerve canal, a CBCT or OPG scan may be advised to show it in more detail; we will tell you where it is done and what it costs.

What happens next

If the tooth is causing harm or is likely to, removal is usually advised. Impacted teeth often need a small surgical procedure: the gum is opened, a little bone is removed, and the tooth may be divided into pieces so it comes out with less force. These cases are planned with our oral and maxillofacial surgery department. Read more on our page on impacted teeth and on our wisdom tooth extraction page.