The removal of impacted third molars is the most common procedure in the specialty of oral and maxillofacial surgery. The use of panoramic radiograph has been recommended as the primary radiographic investigation of choice in the assessment of the impacted mandibular third molar teeth. It is useful to assess the position, depth, and the type of impaction as well as the texture of the investing bone. We have conducted 300 cases of retrospective panoramic radiographic study at Adhiparasakthi dental college and hospital, Melmaruvathur, the main objective of this study to evaluate predictors associated with the impacted mandibular third molars such as age, gender, angulation, root formation, root tip relation to the inferior alveolar canal and measurement of the depth of bone in relation to the impacted mandibular third molar. For all the predictors significant variables are noted and concluded panoramic radiographs can be used as reliable investigation for evaluation of impacted mandibular third molar.