Impacts of non-impacted third molar removal on the periodontal condition of adjacent second molars

Objective The aim of this study was to determine how the removal of non-impacted third molars (N-M3s) affects the periodontal status of neighboring second molars (M2s). Subjects and Methods The periodontal condition of M2s for which the neighboring N-M3s were removed (more than 6 months previously) and those with intact N-M3s was analyzed in a cross-sectional observation study. In an additional case series, periodontal changes in M2s in response to adjacent N-M3 removal were observed during a 6-month follow-up period. Results A total of 457 patients with 1,301 M2s were enrolled in this cross-sectional observational study. Compared to M2s with neighboring N-M3s, M2s without neighboring N-M3s (teeth removed more than 6 months previously) exhibited a 0.27-mm reduction in the average pocket depth (PD) (p < .001) and a 0.38-fold reduced risk of at least one probing site with PD >= 5 mm (PD5+) (p < .001). Subsequently, a 41-case follow-up study showed that 6 months after neighboring N-M3 extraction, the PD of the M2s decreased by 0.31 mm (p < .001), while the incidence of PD5+ decreased by 21.9% when compared to the parameters detected before tooth extraction (p = .004). Conclusions Removing N-M3s was associated with an improved periodontal condition in neighboring M2s.