Third Molars and Periodontal Pathology in American Adolescents and Young Adults: a Prevalence Study

Purpose: To assess the association between visible third molars and the prevalence of periodontal inflammatory disease of non-third molars.

Patients And Methods: Subjects aged 14 to 45 years with 4 asymptomatic third molars were enrolled in an institutional review board-approved study. Subjects were classified based on whether at least 1 third molar was visible or all third molars were not visible. Full-mouth periodontal probing depth (PD) data, with 6 sites per tooth, were obtained as a measure of a subject's periodontal status. At least 1 non-third molar PD of 4 mm or greater was indicative of periodontal inflammatory disease. Outcomes for the respective groups were compared by use of Cochran-Mantel-Haenszel row mean score statistics. The level of significance for differences was set at .05.

Results: The 342 subjects in the visible group were significantly older, with a median age of 26 years (interquartile range, 22.4-32.2 years), as compared with the 69 subjects in the not visible group, with a median age of 21 years (interquartile range, 18.8-24.9 years) (P < .01). The proportion of males and females was not statistically different between groups (P > .05). Most subjects were white. Significantly more subjects with at least a college education were in the visible group than in the not visible group (P < .01). The rate of tobacco use was low and did not differ between groups. Subjects in the visible group were significantly more likely to have at least 1 PD of 4 mm or greater on non-third molars than those in the not visible group: 59% versus 35%. In both groups, first/second molars were more affected than nonmolars when we controlled for differences in age between groups.

Conclusions: The visible presence of third molars in adolescents and young adults was significantly associated with periodontal inflammatory disease of non-third molars.