Impacted Mandibular Third Molar, Associated Pathoses, and Their Relation to Angulation and Impaction Depth: A Cone Beam CT Study

Najmeh Movahhedian, Shoaleh Shahidi, Sadegh Jozari, Alireza Mosharaf, Atefeh Naderi


Statement of problem: prophylactic removal of the impacted lower third molar (ILTM) is controversial and accompanying pathologic conditions play an important role.

Objectives: The aim of the present study is to evaluate the prevalence of commonly found pathoses associated with ILTM in relation to angulation and impaction depth in cone beam computed tomography (CBCT).

Materials and Methods:  We evaluated CBCT of 500 ILTMs from 235 females (57%) and 177 males (43%) for the presence of caries on the second and third molars, external root resorption (ERR) of the second molar, and follicular spaces (FS) >5 mmin diameter in relation to angulation and impaction depth according to Pell and Gregory and Winter’s classifications, respectively.

Results: We observed that 55.6% of ILTM had at least one detectible lesion. ERR was the most frequent pathologic condition (31.2%), followed by caries on the second (26%) and third (13.4%) molars, and FS >5 mm (2.4%). ERR was the only pathology influenced by angulation. There was significantly more ERR in mesioangular ILTMs (40.5%, P<0.001). Most ERR occurred in direct contact with the third molar. Class C showed a lower risk for second and third molar caries (P<0.001), but higher risk for ERR (P=0.008) and FS >5 mm(P=0.035). There were more caries on the second molar (P=0.013) and FS >5 mm (P<0.001) in class III.

Conclusions: Prophylactic removal of ILTMs (especially in mesioangular or horizontal impactions) could be suggested considering the potential for pathologic changes in ILTMs and the propensity for these teeth to cause ERR in second molars.

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