Association between mandibular third molar position and the occurrence of pericoronitis: A systematic review and meta-analysis

•Vertical position of the lower third molar increases the chance of pericoronitis.•Position A had greater chance of pericoronitis compared to position B of third molars.•The prophylactic removal of lower third vertical molar or in position A could prevent pericoronitis. The aim of this study was to investigate the association between mandibular third molar position and occurrence of pericoronitis. The systematic review was performed based on PRISMA criteria (Prospero: CRD42018102835). The electronic search was performed in Medline, Virtual Health Library and Web of Science (until August 2018), without language restriction. Two researchers independently selected studies, extracted data, and assessed methodologic quality. Twenty-one articles were included in the review, comprising 6895 patients, with 1913 third mandibular molars being affected by pericoronitis. Ten studies were incuded in meta-analysis. The third molar in vertical position of Winter is the one with the greatest chance of presenting pericoronitis, compared to the other positions, while the horizontal position decreases this chance. There was no significant difference in the chance of pericoronitis between positions I and II of Pell & Gregory (OR: 0.29; IC: 0.07–1.23, I2 = 88%). Third molars classified in position A had greater chance of pericoronitis when compared to those in position B (OR: 7.13; IC: 1.31–38.74, I2 = 93%). The vertical position of the lower third molar is more associated with the occurrence of pericoronitis when compared to the other positions. Vertical position of the lower third molar is more associated with the occurrence of pericoronitis when compared to the other Winter’ positions. Considering Pell and Gregory positions, position A had a greater chance of pericoronitis compared to position B. The prophylactic removal of lower third semi-erupted vertical molar or in position A is indicated to prevent pericoronitis.