Impacted third molars increase the risk for caries and periodontal pathology in neighboring second molars.

Subjects Thematerial was drawn from the US Department of Veterans Affairs Dental Longitudinal Study beginning in 1969 in Boston, Massachusetts. From a group of 1231 men the authors identified 416 subjects (mean age 45.8 6 7.4 years) who had both first and second molars present in at least one quadrant. Upper and lower quadrants were included. Third molar status (n = 804 teeth) was assessed from panoramic and intraoral radiographs. Subjects were examined clinically every 3 years by a periodontist. Subjects were included in the analysis if they had had at least one follow-up examination.