Analysis of the unpredictable migration of impacted mandibular third molars: A pilot study

Eruption of an impacted mandibular third molar (3MM) is often unpredictable. The objective of this study was to establish the radiographic parameters of migration in patients whose 3MMs evolved unpredictably. This was a retrospective observational study. Patients with unusual 3MM migration (away from their physiological eruption position with changes in the longitudinal and horizontal axes) and with at least two panoramic radiographs were included. To evaluate the radiographic parameters, images were superimposed, using mandibular angle and ipsilateral condyle as references. Of a total of 2851 patients, four were included in our study. The average age of the patients at the time of the second X-ray was 41.75 (SD=8.42) years. The mean follow-up period was 111 (SD=59.09) months. The migration was caudal in three of the 3MMs (75%) and cranial in one (25%). Unpredictable 3MM migration is rare, and occurs mostly in the vertical direction with an average angle of 12 degrees. None of these migrations were related to any type of lesion. Our results reveal that, due to its unpredictable behaviour, impacted wisdom teeth have to be periodically radiographically evaluated even if surgical extraction is not indicated. Tooth migration, third molar, ectopic tooth.