Change in third molar angulation and position in young adults and follow-up periodontal pathology

This study was designed to assess changes in third molar position and angulation in young adults and the resulting third molar periodontal probing (PD) status.

Data derived from patients with 4 asymptomatic third molars with adjacent second molars enrolled in an institutional review board approved longitudinal trial. Inclusion criteria for the trial dictated that patients be healthy and 14 to 45 years of age. Panoramic radiographs were analyzed for third molar angulation as compared with the long axis of the second molar (mesial/horizontal > or =25 degrees ) and eruption to the occlusal plane. Full mouth PD including third molars was conducted at follow-up. At follow-up, PD > or =4 mm distal of second molars or around third molars was considered important clinically.

Data from 237 patients were available. Median age was 25.9 years (interquartile range [IQ], 22.1 years, 32.8 years). With a median follow-up of 2.2 years (IQ, 2.0 years, 3.7 years), 44% of impacted maxillary third and 26% of impacted mandibular third molars changed angulation or position. One third of vertical/distal impacted third molars in both jaws and 11% mesial/horizontal mandibular third molars erupted to the occlusal plane during follow-up from baseline. If mandibular third molar angulation as compared with the long axis of the second molar was mesial/horizontal > or =35 degrees , only 3% erupted to the occlusal plane. At follow-up, 11% of the 125 impacted maxillary third and 29% of the 133 impacted mandibular third molars had PD > or =4 mm. Similarly, 11% of the 307 maxillary third molars at the occlusal plane had PD > or =4 mm, but 51% of the 312 erupted mandibular third molars were affected.

A change in third molar position or angulation was common. Erupted mandibular third molars were more likely to have PD > or =4 mm.