Periodontal pathology associated with asymptomatic third molars

Abstract

Purpose: We report the prevalence of periodontal probing depth (PD) as a clinical measure of the extent of periodontitis associated with asymptomatic third molars at the initial examination in a cohort of patients enrolled in an institutional review board-approved longitudinal clinical trial.

Patients and methods: Three hundred twenty-nine healthy patients were enrolled during a 30-month period. Full mouth periodontal probing that included third molars was conducted to determine periodontal status. Panoramic radiographs were taken to assess the degree of eruption of the third molars and the angulation of third molars compared with the adjacent second molar. Vertical bitewing radiographs were analyzed to detect alveolar bone levels relative to the cementoenamel junction on the distal of second molars.

Results: Twenty-five percent (82 of 329) of all enrolled patients, and 34% (14 of 41) of black patients, had at least one PD equal to or greater than 5 mm on the distal of a second molar or around a third molar. PD equal to or greater than 5 mm was associated with periodontal attachment loss of at least 1 mm in every patient; PD equal to or greater than 5 mm was associated with attachment loss equal to or greater than 2 mm in 80 of 82 patients. A higher proportion of patients 25 years old or older had a PD equal to or greater than 5 mm on the distal of second molars or around third molars compared with patients younger than 25 years (33% vs 17%, P =.002). The distals of second molars and third molars in the mandible were affected more often than in the maxilla (25% vs 5%, P =.0001).

Conclusions: Our data indicating that 25% of patients with retained asymptomatic third molars have considerable periodontal pathology in the third molar region were unexpected. National epidemiologic surveys indicate a much lower rate of periodontitis in the population younger than 35 years.