Wisdom tooth

The age at which wisdom teeth come through (erupt) is variable,[1] but this generally occurs between late teens and early twenties.

Some sources oppose the prophylactic removal of disease-free impacted wisdom teeth, including the National Institute for Health and Care Excellence in the UK.

With the Industrial Revolution, the affliction became ten times more common, owing to the new prevalence of soft, processed foods.

Maxillary (upper) third molars commonly have a triangular crown with a deep central fossa from which multiple irregular fissures originate.

If impacted and having a pathology, such as caries or pericoronitis, treatment can be dental restoration for cavities and for pericoronitis, salt water rinses, local treatment to the infected tissue overlying the impaction,[33]: 440–441  oral antibiotics, surgical removal of excess gum flap (operculectomy), or if those failed, extraction or coronectomy.

There are different types of odontogenic infections which may affect impacted wisdom teeth such as periodontitis, pulpitis, dental abscess and pericoronitis.

[37][38] They are described as ‘cavities filled with liquid, semiliquid or gaseous content with odontogenic epithelial lining and connective tissue on the outside’.

Removal of asymptomatic impacted wisdom teeth with the absence of disease and no evidence of local infection as a prophylactic method has been disputed within the dental community for a long time.

There is insufficient reliable scientific evidence for dental health professionals and policy makers to determine if asymptomatic disease-free impacted wisdom teeth should be removed.

Considering the lack of quality evidence at present, more long-term studies need to be undertaken to obtain a reliable scientific conclusion.

[40] Platelet-rich fibrin (PRF) is a postoperative method used to heal the alveolar socket following the removal of the mandibular third molar.

Studies have shown that when used there are improvements in pain sensations, swelling and a decreased risk of developing dry socket.

To date there is no clear correlation between the use of PRF after a mandibular third molar removal surgery and the recovery of jaw spasms, bone restoration and soft tissue healing.

[42] Temporary and permanent inferior alveolar nerve (IAN) damage is a known complication of the surgical removal of impacted lower third molars, happening in 1 in 85 patients and 1 in 300 extractions, respectively.

Proximity of the impacted third molar root to the mandibular canal, which can be seen in radiographs, has been shown to be a high-risk factor for IAN damage.

Alongside this, the depth of impaction of the tooth, surgical technique and surgeons experience are all contributing risk factors for IAN damage during this procedure.

In the 1970s it was thought that unerupted wisdom teeth produced a forward directed force which would cause crowding of the anterior segment.

3D CT of an impacted wisdom tooth near the inferior alveolar nerve
Inflamed excess gum flap (inflamed operculum marked by green arrow) over wisdom tooth
Some problems which may or may not occur with third molars: A Mesio-impacted, partially erupted mandibular third molar, B Dental caries and periodontal defects associated with both the third and second molars, caused by food packing and poor access to oral hygiene methods, C Inflamed operculum covering partially erupted lower third molar, with accumulation of food debris and bacteria underneath, D The upper third molar has over-erupted due to lack of opposing tooth contact, and may start to traumatically occlude into the operculum over the lower third molar. Unopposed teeth are usually sharp because they have not been blunted by another tooth.
Dental x-ray of impacted lower left wisdom tooth with a horizontal orientation
The upper left (picture right) and upper right (picture left) wisdom teeth are distoangularly impacted. The lower left wisdom tooth is horizontally impacted. The lower right wisdom tooth is vertically impacted (unidentifiable in orthopantomogram ).