Impacted Wisdom Teeth Guide: Types of Sideways and Buried Teeth and Deciding on Removal
An impacted wisdom tooth is one that cannot erupt properly and stays partly or fully buried in gum or bone because the jaw lacks space. The Korea Disease Control and Prevention Agency (KDCA, 질병관리청) explains that in the lower jaw, forward-tilted mesioangular impaction is most common, followed by horizontal and vertical. An impacted wisdom tooth can cause decay in the molar in front, recurring gum inflammation and cysts in the jawbone, so position and risk are checked on X-rays before deciding whether to extract.
Key facts
| Lower jaw impaction classification | Vertical, tilted toward the cheek, tongue, front or back, transverse, horizontal, inverted (source: KDCA National Health Information Portal) |
|---|---|
| Most common form | Mesioangular (tilted forward), followed by horizontal and vertical (source: KDCA National Health Information Portal) |
| Dentigerous cyst | Destroys surrounding jawbone, and when large, even a small impact can break the jaw (source: KDCA National Health Information Portal) |
| Fully impacted tooth extraction (insurance item) | When a tooth with at least two thirds of the crown buried in alveolar bone is removed with both bone removal and tooth sectioning (source: Health Insurance Review and Assessment Service (HIRA, 건강보험심사평가원)) |
| Complex impacted tooth extraction (insurance item) | When tooth sectioning is performed (source: HIRA) |
Why do wisdom teeth become impacted?
Wisdom teeth are the last teeth to form inside the jawbone. The KDCA explains that because the jaw has been getting smaller while tooth size stays the same, a mismatch leaves too little space, and wisdom teeth can become impacted or change position.
An anthropological explanation is also introduced that the shrinking of the jaw has accelerated as people eat soft, refined food. In most civilized populations, about 30% of people are said to have no wisdom teeth at all.
When jaw space is lacking, a wisdom tooth either breaks through the gum and only partly emerges or stays entirely within the bone. This is usually first confirmed on X-rays taken around the time wisdom teeth would erupt, in the late teens to early 20s.
What types of impacted wisdom teeth are there?
Lower impacted wisdom teeth are classified by the direction of tilt. Frequencies differ by study, but the KDCA explains that forward-tilted mesioangular impaction is most common, followed by horizontal and vertical, while backward tilt, transverse and inverted impaction are relatively rare. Besides the tilt, the difficulty of extracting an impacted wisdom tooth varies with the number, length and shape of roots, the condition of the bone behind it and the distance to the mandibular canal.
- Mesioangular: tilted toward the molar in front, trapping food and making decay of that molar likely
- Horizontal: lying completely on its side, often requiring the tooth to be removed in sections
- Vertical: standing upright but covered by gum or bone
- Distoangular: tilted backward, making inflammation at the front edge of the jawbone likely
What risks come from leaving an impacted wisdom tooth?
A wisdom tooth only partly covered by gum collects food and bacteria between tooth and gum, making inflammation likely to recur. The KDCA warns that recurring surrounding inflammation can become severe enough to swell the face and neck.
A dentigerous cyst, that is, a fluid-filled sac, forming around an impacted wisdom tooth can destroy surrounding jawbone and spread to the neighboring molar, causing tooth loss. When the cyst grows, even a small impact can break the jawbone, so prompt treatment is needed once it is found.
Must every impacted wisdom tooth be removed?
The KDCA lists pericoronitis, cysts or tumors, infection, and cases where removal is needed for the stability of orthodontic treatment or for treatment of the molar in front as indications for extracting an impacted wisdom tooth. If there are no such problems and the tooth is deeply embedded with a high risk of nerve damage, it can be left in place and monitored.
Not extracting is considered when damage to major structures is expected, when too much jawbone would have to be removed, or when the patient's general condition makes extraction hard to tolerate. In the end, the benefit and risk of removal are weighed and decided together with the dentist.
Is impacted wisdom tooth extraction covered by health insurance?
Yes. In HIRA review cases, impacted wisdom tooth extraction is billed under different items depending on impaction level, such as a complex impacted tooth removed in sections, or a fully impacted tooth with at least two thirds of the crown buried in bone, removed with both bone removal and sectioning.
The patient's share is calculated by the outpatient copayment rate, such as 30% at dental clinics and 40% at dental hospitals in dong areas in Korea. The cost changes if a CT is needed because of proximity to the nerve canal or if you are referred to a higher-level facility, so check before extraction.
Common myths and facts
Myth: A wisdom tooth you cannot see does not cause problems.
Even a wisdom tooth buried in bone can form a cyst around it or damage the root area of the molar in front, so checking with X-rays is advisable.
Myth: An impacted wisdom tooth must always be removed.
If it is deeply buried, causes no problems and has a high risk of nerve damage, it may be left in place and monitored.
Frequently asked questions
How do I know if I have an impacted wisdom tooth?
For a wisdom tooth that is only partly visible or not visible at all in the mouth, position and tilt are checked on a panoramic X-ray. If it is close to the nerve canal, a dental CT may be added.
Does removing a sideways wisdom tooth take long?
The KDCA explains that horizontal impaction requires sectioning the crown and may need more bone removal, so it can take a long time. The exact time is explained by the dentist who has reviewed the X-rays.
My molar in front is sensitive. Could an impacted wisdom tooth be related?
If a forward-tilted wisdom tooth causes decay on the back of the molar in front, that molar can become sensitive or painful. The KDCA explains that in this case the front molar has likely already been damaged, so get it examined.
The area around my impacted wisdom tooth often swells. What should I do?
It may be pericoronitis, inflammation between the tooth and gum. The usual order is to treat the inflammation first and consider extraction if it recurs. If swelling reaches the face or neck and you have a fever, do not wait; see a dentist immediately.
Can impacted wisdom teeth occur in the upper jaw too?
Yes. Upper wisdom teeth are sometimes close to the maxillary sinus, so the distance to the sinus is also checked when planning extraction. The KDCA explains that even if a root fragment enters the sinus, if it is small, about 1 to 3 mm, and causes no problems, it can be monitored.
Related topics
- Wisdom Tooth Extraction
- Wisdom Tooth Extraction
- Wisdom Tooth Extraction Procedure
- Nerve Damage Risk
- Wisdom Tooth Extraction Cost and Insurance