Prediction of mandibular third molar impaction in the orthodontic patient from a panoramic radiograph

In this study we explored the predictability of mandibular third molar impactions. Serial panoramic radiographs from 50 non-extraction and 15 extraction patients were traced for various angular and linear measurements. A linear discriminant function analysis was performed for each stage of third molar development. The results indicate that the earliest stages of development have very little predictive value. Accordingly, a justification for the oft-practiced enucleation procedure cannot be made. Although the more the tooth is developed, the higher is the accuracy of prediction, two earlier stages where the crown is fully formed or the roots 1/3 formed possess high predictive values. Based on our data, impaction of third molars in the mandible is a predictable event both in extraction and non-extraction patients.