BACKGROUND: Management of mandibular third molar teeth requires accurate and precise information regarding exact location and its relationship with the inferior alveolar nerve (IAN) where these two structures are intimately related to prevent the injury of the nerve. For pre-operative screening of the cases, intraoral and panoramic radiograph is sufficient to determine the position of the third molar in relation to inferior alveolar nerve. But with advent of cone beam computed tomography (CBCT), it has become easy to localize the exact position of the tooth and IAN in all the three planes where both are closely related.
AIM: The aim of the study was to evaluate the diagnostic utility of CBCT in preoperative assessment of impacted mandibular third molars where root tip is in direct proximity of the IAN as evaluated in panoramic radiograph.
MATERIALS AND METHODS: Study sample was composed of 20 patients (40 teeth). High risk signs of IAN injury such as darkening of roots, interruption of white line of mandibular canal, superimposition of roots on mandibular canal, narrowing of mandibular canal, and deviation of mandibular canal were assessed in panoramic radiograph and subsequently CBCT images were evaluated for exact location of mandibular canal in relation to root tip, cortical lining of mandibular canal, and cortical plate perforation.
RESULTS: In most of the cases mandibular canal in relation to root tip was at the level of roots and inferiorly positioned. There was statistical significant association between darkening of roots and cortical plate perforation, interruption of white line and absence of corticalisation of mandibular canal and superimposition of roots on mandibular canal and presence of corticalisation of mandibular canal.
CONCLUSION: In the present study, exact localization of mandibular canal was done in relation to the mandibular third molar in all three planes with the help of CBCT in the cases showing the high risk signs of IAN injury. CBCT proved to be a promising diagnostic tool for preoperative assessment of mandibular third molar tooth and IAN in complicated cases
