Influence of mandibular third molar surgical extraction on the periodontal status of the adjacent second molars

BACKGROUND: The periodontal health distal of second molars (M2) is often compromised due to third molar (M3) impactions. The aim of this study was to evaluate healing and periodontal status of mandibular M2 after M3 surgical extraction. METHODS: Eighty-nine consecutive patients with 89 asymptomatic M3 who needed surgical extraction of one fully- or semi-impacted M3 entered this study. Clinical measurements, probing pocket depth (PPD), clinical attachment level (CAL), plaque index (PI), gingival index (GI) and bleeding on probing (BOP), were compared for M2 at baseline (T0) and six-months (T1) post-surgical extraction. Multiple logistic regression analysis assessed different risk factors for post-operative changes of periodontal parameters. RESULTS: Six-month M2 PPD improved at disto-vestibular (T0-5.2/T1-3.0mm) and disto-lingual (T0-5.4/T1-3.2mm) sites. The average attachment gains at T1 were 1.9mm and 2mm, respectively (p < 0.05). BOP, PI and GI showed significant clinical improvements after extractions. Fifty-three out of 72 (73.6%) M2 presenting a PPD ≥ 4mm at baseline healed at six months recall without periodontal pockets. Older age (mean 55 years, SD 16.7; range 26-81) and mean distal PPD at baseline of 7mm was more likely to be associated with PPD≥4mm six months post-extraction (p < 0.05). Past history of periodontitis patients were 41 times more likely to present PPD≥4mm after healing (OR = 41.4; 95%CI = 10.9-156.5, p < 0.05). CONCLUSION: Mandibular M3 extractions seem to improve overall periodontal health distal of M2 History of periodontitis, preoperative deep pockets and older age are independent risk factors for poorer healing and residual pockets after M3 surgical extraction.