Radiologic assessment of mandibular third molars: an ex vivo comparative study of panoramic radiography, extraoral bitewing radiography, and cone beam computed tomography

Abstract

Objectives: The aim of this study was to compare the performance of panoramic radiography (PAN), extraoral bitewing radiography (EBW), and cone beam computed tomography (CBCT) in the assessment of mandibular third molars.

Study design: PAN and EBW were obtained to visualize 34 third molars. The teeth were evaluated by using PAN and EBW according to their positions, the presence of radiographic signs of proximity of the roots to the mandibular canal, the relationship of the roots to the canal, and the relationship of the second and third molars. Third molar position and root relationship with the canal were also assessed with CBCT.

Results: PAN and EBW showed significantly closer relationships compared with CBCT between the tooth and the mandibular canal (P ≤ .002). With regard to all other parameters, no differences were seen between PAN and EBW (P ≥ .072), although EBW, in comparison with PAN, showed a decreased overlap between the proximal surfaces of the second and third molars and a greater trend toward approximating root apices and the canal.

Conclusions: In comparison with PAN, EBW showed a tendency to project the roots closer to the mandibular canal, but there was a decrease in the proximal surfaces overlapping the second molar. The relationship between the third molar and the mandibular canal appeared closer in PAN and EBW than in CBCT.