Evaluation of the ability of panoramic radiography to show the real relationship between embedded wisdom teeth and inferior alveolar canal by using a surgical technique

Introduction: Close proximity between third molars and inferior alveolar canal is common. It is important to prevent damage to the inferior alveolar nerve during surgery.  This research was undertaken to show the efficacy of panoramic radiography technique in demonstrating the relationship between impacted third molars and inferior alveolar canal by using a surgical technique.   Materials and Methods: Sixty patients, referring to Isfahan Faculty of Dentistry and the relevant clinic during 2011-2012 educational year, were selected for this descriptive/analytical study by a radiologist; the subjects had at least one sign about the close proximity between the inferior alveolar canal and the tooth on their panoramic radiographs. The third molars were surgically extracted by a maxillofacial surgeon and the existence or non-existence of close proximity between the tooth and the canal was recorded as a gold standard. McNemar’s test was used to evaluate the diagnostic power of the radiographic technique (α = 0.05). Results: The positive predictive value for superimposition of tooth image on the upper rim of the canal (p value = 0.1), superimposition of the tooth image on the entire canal (p value < 0.001) and superimposition of the tooth image on the entire canal along with narrowing of the alveolar canal (p value = 0.013) had higher diagnostic values compared to other signs, with positive predictive values 59.3%, 86.3% and 54.5%, respectively.  Conclusion: Under the limitations of this study, it can be concluded that superimposition of tooth images on the entire alveolar nerve canal with narrowing and deviation of the canal can indicate a real relationship between the tooth and the canal.     Key words: Anatomy, Impacted tooth, Inferior alveolar nerve, Oral surgery, Panoramic radiography