Radiographic Comparison of the Relation between Mandibular Third Molar Root and Inferior Alveolar Canal in Panoramic Radiography and Cone-Beam Computed Tomography

There is a risk of damage to the inferior alveolar nerve when extracting third molars. A variety of common imaging modalities, such as panoramic radiography (PR) and cone-beam computed tomography (CBCT), are recommended for examination prior to mandibular third molar surgery. The aim of this study was to compare the findings of panoramic radiography and CBCT in evaluating the relation between the root of the mandibular third molar and the inferior alveolar canal.

In this cross-sectional study, 75 panoramic and CBCT images were evaluated. Cases in panoramic radiography that were suspected of the relation between the root of the mandibular third molars and the inferior alveolar canal were collected. To determine the type of connection of apex and root canal, the samples were divided into 6 groups: normal, inferior alveolar canal path loss, canal path narrowing, sudden canal path change, radiolucent band over the roots, and root curvature. Cases in the panoramic radiograph that were suspected of root contact with the canal were examined by the CBCT in terms of the position of the canal relative to the tooth (buccal or lingual or middle of the root - upper or lower) and the type of connection (whether the tooth is connected to the canal).

In panoramic findings, 23 cases (30.7%) were normal, 19 cases (25.3%) showed canal path loss, 9 cases (12%) canal path narrowing, 5 cases (6.7%) sudden canal path change, 3 cases (4%) radiolucent band over the roots and 16 cases (21.3%) showed root curvature. According to CBCT findings, the position of the canal relative to the root apex was lingual in 39 cases (52%) and there was connection between the mandibular canal and the third molar in 39 cases (78.7%). There was no significant relationship between panoramic radiographic and CBCT findings and only in two cases of specific radiolucent band over the roots, there was a complete agreement between panoramic and CBCT findings.

Based on the results of this study, if a radiolucent band is observed on the root of the mandibular molars or a sudden change is observed in the canal path, panoramic radiography can be used to detect the relation between the inferior alveolar canal and the root of the third molars.