October 2023

Objective: To compare bone level changes and probing depths at the adjacent mandibular second molar (M2) 6 months after impacted mandibular third molar (M3) extraction between patients with and without periodontitis. Material and Methods: Patients referred for extraction of M3 were recruited. Patients were categorized as periodontally susceptible (PSP) or healthy patients (PHP). Six months after surgical extraction of M3 (T1), periodontal probing depths (PPD) and radiographic bone level at M2 were compared between the two groups. Regression analyses were performed to identify factors associated with PPD and bone level changes. Results: 42 patients completed the study, and the mean follow-up duration was 6.7 months. There was no significant difference in radiographic bone gain at M2 between PSP and PHP patients (1.26mm vs 1.13 mm). Every 1% increase in full mouth bleeding score at T1 was associated with 2.64mm less bone gain at M2. The PSP group was 6.43 times more likely to have PPD ≥ 5 mm at T1. Conclusions: Second molars in patients with periodontitis were not associated with less bone level gain 6 months after extraction of impacted M3. However, second molars in patients with higher gingival inflammation were associated with less bone gain.