Utility of Denta Scan in Evaluating Relationship of Inferior Alveolar Canal and Impacted Mandibular Third Molar Roots
Author(s): Anuraag Bhaskar Choudhary*, Mukta B Motwani, Trupti Chordia, Mayur B Chaudhary, Pankaj Banode, Manoj Patil
Background: The impacted mandibular third molar may cause pathologies like pain, pericoronitis, periodontal infection, periapical infection, cellulitis, orthodontic problems and facilitation of fracture of mandible at the angle of mandible, cyst and tumour from the tooth germ or follicle or from tooth itself. Any of these reasons could necessitate the extraction of the tooth, which could be either intentional or prophylactic. This study tried to evaluate the necessity of using CT as against only panoramic radiographs and the diagnostic accuracy of panoramic radiography for pre-operative assessment of patients with impacted mandibular third molars showing close approximation to the Inferior Alveolar Canal (IAC).
Objectives: To evaluate the relationship of inferior alveolar canal to the impacted mandibular third molar root using radiographic markers on rotational panoramic radiographs (OPG) and assessing its true relationships on Computed Tomography (Dental CT) scan.
Methods: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using OPG and on confirming the intimate relationship of third molar root relation to inferior alveolar canal, denta scan CT was done to determine the spatial relationship and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available.
Results: The 40 patients referred had 70 impacted, various radiographic markers used to determine the relation of inferior dental canal to the impacted mandibular third molar roots using OPG like S-Superimposition of canal on roots, Na-Narrowing of canal, R-Reduction in density of roots, D-Deviation of canal along with combination markers like S and R-Superimposition with Reduction in density of root, S and N-Superimposition with narrowing and S and D-Superimposition with Deviation using Chi square test (χ2). There markers were compared with CT findings of Contact (C), Narrowing (N) and Thinning (T). Sensitivity and specificity of OPG was also evaluated with respect to CT markers using fisher’s exact test for accuracy using graph pad prism software.
Conclusions: Contacting of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs S and N of the inferior dental canal is the best predictor of contact of the inferior dental canal and its close relationship to the roots.