Wisdom teeth, also called third molars, are the last adult teeth to develop. By the time they begin to erupt, there may be insufficient space at the back of the jaw for them to come through properly. A tooth can therefore remain partly covered by gum tissue, trapped beneath the gums or positioned against another tooth.
The exact wisdom teeth position is important because it can influence how easy the tooth is to clean, whether it affects neighbouring teeth and how complex treatment may be if removal becomes necessary.
The main types of impacted wisdom teeth are commonly described according to their angle, including mesioangular, vertical, distoangular and horizontal impactions. A dentist uses a clinical examination and dental imaging to assess the individual position of the tooth.
What Is Tooth Impaction?
Tooth impaction occurs when a tooth does not erupt into its normal position within the dental arch. For wisdom teeth, this often happens because there is insufficient room behind the second molars. The developing wisdom tooth may also be blocked by another tooth or follow an angle that prevents normal eruption. An impacted tooth may be:
- Completely beneath the gum
- Partly covered by gum tissue
- Partially visible in the mouth
- Pressed against the tooth in front
- Positioned at an unusual angle within the jaw
Not every impacted tooth causes symptoms. Some impacted wisdom teeth remain healthy and are monitored during routine dental examinations. Others can be associated with infection, decay, gum problems or damage to neighbouring teeth.
Types of Impacted Wisdom Teeth
The types of impacted wisdom teeth are often classified according to the direction in which the tooth is angled. The four commonly described positions are:
- Mesioangular
- Vertical
- Distoangular
- Horizontal
A tooth’s angle is only one part of the assessment. Its depth within the jaw, relationship with neighbouring teeth and proximity to important anatomical structures can also affect treatment planning.
Mesioangular Impacted Wisdom Tooth
A mesioangular impaction occurs when the wisdom tooth is angled forwards towards the tooth immediately in front of it. In the lower jaw, this means the crown of the wisdom tooth may lean towards the second molar. This position can prevent the wisdom tooth from erupting fully. A mesioangular tooth may remain partly erupted or be completely trapped beneath the gum and bone. The position can also make cleaning the area more difficult.
Vertical Impacted Wisdom Tooth
A vertically impacted wisdom tooth is positioned relatively upright but is unable to erupt normally. The tooth may have the correct general direction for eruption but remain trapped because there is insufficient space. It can be covered by gum tissue, bone or both. A vertical impaction does not automatically mean that the tooth needs to be removed. Some vertically positioned wisdom teeth remain free from disease and can be monitored.
Distoangular Impacted Wisdom Tooth
A distoangular impaction occurs when the wisdom tooth is angled backwards towards the rear of the jaw. This position is less common than some other forms of impaction and can make access more challenging if the tooth requires removal. The angle alone does not determine whether a tooth will cause problems. A distoangular wisdom tooth may remain symptom-free, while another tooth in the same general position may be associated with disease. I
Horizontal Impacted Wisdom Tooth
A horizontal impacted wisdom tooth lies almost sideways within the jaw. The crown may face directly towards the roots or side of the second molar. Because of this position, the tooth may be unable to erupt normally. A horizontal impaction can place the wisdom tooth in close contact with the neighbouring molar. This may make the area difficult to clean and, in some cases, contribute to problems affecting the adjacent tooth.
Partially Impacted Wisdom Teeth
Partially impacted wisdom teeth have emerged to some extent but cannot erupt completely into their normal position. A partially emerged wisdom tooth may have a section of gum tissue covering part of the crown. This creates an area where food debris and bacteria can become trapped. The gum surrounding the tooth may become inflamed or infected, causing a condition known as pericoronitis. Symptoms can include tenderness, swelling, discomfort when chewing and difficulty cleaning the back of the mouth.
Fully Impacted Wisdom Tooth
A fully impacted wisdom tooth remains completely beneath the gum and may also be covered by jawbone. The tooth may not be visible during a routine examination, which is why X-rays can be important when assessing its position. A fully impacted tooth can remain symptom-free. In the absence of disease, routine removal is not generally recommended solely because the tooth is impacted.
Impacted Upper Wisdom Teeth
Impacted upper wisdom teeth are positioned in the upper jaw rather than the lower jaw. Their anatomy and relationship with surrounding structures differ from impacted lower wisdom teeth. The direction of the tooth, depth of impaction and access available at the back of the upper jaw can all influence treatment planning. An upper wisdom tooth may become trapped against the tooth in front or remain partly or completely beneath the gum.
How Dentists Assess Wisdom Teeth Position
A dental examination can provide information about whether a wisdom tooth has erupted and whether the surrounding gum appears healthy. However, an impacted wisdom tooth X ray is usually needed to assess teeth that are partly or completely beneath the gums. Dental imaging can show:
- The angle of the wisdom tooth
- How deeply it is positioned
- Its relationship with the second molar
- The shape and development of its roots
- Its relationship with surrounding bone
- Whether there are signs of disease associated with the tooth
In more complex cases, a dental CT scan may provide detailed three-dimensional information about an impacted tooth and the surrounding anatomical structures. Perfect Smile specifically lists impacted or unerupted teeth among the concerns assessed using CT imaging.
Does the Type of Impaction Determine Whether a Wisdom Tooth Must Be Removed?
No. The wisdom teeth position does not, by itself, determine whether a tooth needs to be extracted. A deeply impacted tooth can remain healthy for years, while a partly erupted tooth may repeatedly become infected. Treatment decisions should consider:
- Current symptoms
- Evidence of infection
- Tooth decay
- Gum disease
- Damage to neighbouring teeth
- Cysts or other associated pathology
- The potential risks of surgery
NICE guidance recommends against routinely removing pathology-free impacted wisdom teeth. When there is no evidence of disease, regular monitoring may be more appropriate than preventive surgery.
How Can the Type of Impaction Affect Removal?
If surgical treatment is required, the procedure may involve accessing the tooth through the gum, creating sufficient access around the tooth and, where necessary, dividing the tooth into sections before removal. For a full explanation of when removal may be recommended, what surgery involves, recovery and potential risks, see our guide to Pulling Impacted Wisdom Teeth.
When Should You See a Dentist About an Impacted Wisdom Tooth?
Arrange a dental assessment if you experience:
- Persistent or recurring pain at the back of the mouth
- Swelling around a wisdom tooth
- Difficulty opening your mouth
- A bad taste associated with pain or swelling
- Repeated infection around a partially erupted tooth
- Difficulty cleaning the area
- Pain affecting the neighbouring molar
Urgent assessment may be needed if swelling is severe or worsening, or if symptoms are accompanied by difficulty swallowing or breathing.
Types of Impacted Wisdom Teeth: Understanding Your Treatment Options
Understanding the types of impacted wisdom teeth can help explain why one person’s wisdom tooth may be monitored while another requires treatment. Mesioangular, vertical, distoangular and horizontal positions describe the general angle of the tooth, while partial and full impaction describe how much of the tooth has emerged.
However, the classification is only one part of the clinical picture. The health of the tooth, its effect on neighbouring structures and the risks associated with treatment are equally important. If you have been told that you have an impacted wisdom tooth, a dental examination and X-ray can establish its position and whether any treatment is required.
