The third molars are the most common teeth that are found to be impacted. This article will provide and introduction to this topic. The difference between simple and surgical extraction along with the aetiologies and frequency of third molar impaction are explained in a simple way.
An impacted tooth is a tooth that fails to erupt into the dental arch within the expected time frame.
Exodontia can be defined as the clinical practise of extracting teeth and tooth fragments. The ideal aim of exodontia is to remove the entire tooth with minimal trauma to surrounding tissues. It can further be subdivided into simple and surgical exodontia.
Simple exodontia is also known as intra-alveolar extraction. It encompasses the removal of teeth from their bony alveolar sockets without the need to create a surgical pathway for the removal of the teeth. Mostly, the simple extractions are done on the erupted teeth where the entire clinical crown of the tooth is visible.
Surgical exodontia includes the removal of the teeth or tooth fragment(s) through the trans-alveolar approach. In surgical exodontia, access to and removal of the tooth or its fragment(s) is achieved through a surgically created pathway.
We perform surgical extraction on difficult erupted teeth, retained roots, retained tooth fragments, and impacted teeth. Difficult tooth will be a tooth whose crown is fully visible in the mouth, that, for any reason, cannot be completely removed by the intraoral approach alone.
Impacted Third Molar
The relatively soft diet of modern humans has resulted in the evolution of decreased jaw size. The reduced jaw size often results in insufficient space for the full eruption of a third molar into the mouth. Third molars are the most common teeth that are impacted among all teeth. Their eruption time varies greatly and are unpredictable, particularly in individuals who have full compliments of teeth.
Aetiologies of Impaction
The most common aetiology of impaction of third molar is the apparent lack of space in the dental arch for these teeth to come out into a functional position. The other causes of third molar impaction are as follows:
- Obstruction to the path of normal eruption
- Stunted growth of tooth germ
- Rare disorders
Obstruction to the path of normal eruption may be caused by adjacent tooth, supernumerary tooth or any pathological lesions; for example, odontome, & cysts or tumours.
Stunted growth of tooth germ may be caused by severe nutritional deficiency, irradiation or physical trauma.
Rare disorders include cleidocranial dysostosis, hemifacial microsomia, mucopolysaccharidoses and cretinism.
Frequency of Impaction
The third molars are the most common teeth that are found to be impacted. They are 5-6 times more likely to be impacted than maxillary canines which are the second most commonly found impacted teeth. The third most commonly found impacted teeth are the premolars. The probability of premolars to be impacted are 17 times less than that of third molars. When we compare the mandibular vs. maxillary third molars, the mandibular ones are found impacted, 2-3 times more than that of maxillary ones.
The prevalence of third molar impaction ranges from 16.7% to 68.6% . Most studies have reported no sexual predilection in third molar impaction .
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