Five-Years Periodontal Outcomes of Early Removal of Unerupted Third Molars Referred for Orthodontic Purposes.

PURPOSE: The removal of third molars (M3) is one of the most common oral-maxillofacial surgical procedures affecting periodontal tissues of neighboring second molars (M2). The aim of this study was to evaluate the periodontal status of lower M2 following the removal of unerupted lower M3 up to 5 years after removal. PATIENTS AND METHODS: Primary predictor variable in this prospective cohort-study was time [baseline (BL; preoperatively), 6 and 60 months postoperatively]. The primary outcome variable was probing pocket depth (PPD). Clinical attachment level (CAL) was defined as a secondary outcome variable. Plaque index (PlI) and gingival index (GI) were assessed descriptively. All variables were compared using nonparametric tests. M3 were classified as either completely bony or partially bony unerupted. Risk factors (removed M3, type of impaction, mean BL PPD>/=4 mm, gender, age) were analyzed (repeated measures ANCOVA). The significance level was set at 0.05. RESULTS: From originally 91 subjects enrolled in this study, 39 subjects (22 females; mean age: 21.6 +/- 2.5 years) contributing 39 M3 completed the study after 5 years. Average BL PPD significantly decreased at 6 (-0.50 +/- 0.61 mm, P = .001), 60 months (-0.81 +/- 0.56, P < .0001), as well as between 6 and 60 months (-0.31 +/- 0.51 mm, P = .030). Corresponding CAL values decreased accordingly (BL-6 months: -0.37 +/- 0.59 mm, P = .004; BL-60 months: -0.67 +/- 0.55 mm, P < .0001; 6 to 60 months: -0.34 +/- 0.48 mm, P = .004). The was confirmed as risk factor for PPD (P = .026) and CAL (P = .042) changes. CONCLUSIONS: Average PPD and CAL of mandibular M2 in young subjects improved 5 years after early removal of unerupted M3 in favor of an initial partially bony unerupted type of impaction.