Retrospective Analysis on Inferior Third Molar Position by Means of Orthopantomography or CBCT: Periapical Band-Like Radiolucent Sign

Abstract

Background: Orthopantomography (OPG) is usually used as a primary diagnostic radiological exam in the planning of third molar surgery because it is deeply available in dental clinics and has lower radiation doses compared to Cone-beam computed tomography (CBCT). The OPG provides a bi-dimensional image, but several radiological signs have been proposed to study the position of the lower third molar and to predict surgical risks. Methods: Patients were divided into two groups, the OPG with a radiolucent area (D-group) and the OPG without any sign (C-group) in correspondence of inferior wisdom tooth roots. Results: The mean distance between the inferior third molar root and the lingual cortical mandibular bone was −1.09 ± 1.5 mm. The nearness of the root that is less than 1 mm was more frequent in the D-group (84.85%) compared to the C-group (14.58%) with statistical significance (Odd ratio: 32.8) using the Chi-square test. Conclusions: When the root of the impacted inferior third molar is impacted into the lingual cortical plate, a periapical band-like radiolucent sign may appear in the OPG image. It could be useful for the prediction of root position and surgical risks.