Impact of Removal of Asymptomatic Third Molars on Periodontal Pathology

Purpose

This study assessed the impact of third molar removal on periodontal pathology in subjects with third molars asymptomatic at enrollment.

Patients and Methods

Subjects in whom at least 2 third molars were removed were a subsample of healthy young subjects enrolled with 4 asymptomatic third molars in an institutional review board-approved longitudinal study. Full-mouth periodontal probing (PD) data, 6 sites per tooth, were obtained as a measure of periodontal status at each of 3 visits: enrollment, before removal of third molars, and after removal of third molars. Data were aggregated to subject and jaw levels. The oral cavity was divided by jaw into segments: the third molar region including the third molar (12 probing sites), distal to the second molar (4 probing sites), and non-third molars (80 probing sites). A PD ≥4 mm was considered an indicator variable for periodontal pathology. The number and percent of sites with a PD ≥4 mm were calculated from the total number of probing sites across all subjects. The frequency of subjects with at least one PD ≥4 mm and all third molars removed were compared with the frequency of subjects retaining at least 1 mandibular third molar using Fisher's exact test, with significance set at 0.05.

Results

Sixty-nine subjects had third molars removed: 57% were female, and 77% were Caucasian. The median age at surgery was 26.3 years (interquartile range, 23.3-31.5 yr). The median interval from enrollment to surgery was 2.4 years (interquartile range, 1.5-4.2 yr). The median follow-up after surgery was 9 months (interquartile range, 6.7-15.4 mo). All third molars were removed in 56 subjects; 13 retained at least 1 mandibular third molar. More subjects had at least 1 PD ≥4 mm around their mandibular third molars before surgery compared with enrollment (52% vs 45%, respectively). Of the total possible mandibular third molar probing sites, 18% had PD ≥4 mm presurgery compared with 12% at enrollment. Significantly fewer subjects who had all third molars removed had a PD ≥4 mm on the distal of their mandibular second molars after surgery, compared with those retaining at least 1 mandibular third molar (20% vs 69%, respectively, P = .001). The number of PDs ≥4 mm in the mandible was less after surgery if all third molars had been removed (1.4% vs 6.6%, respectively).

Conclusion

Removal of the mandibular third molars significantly improved the periodontal status on the distal of second molars, positively affecting overall periodontal health.