Risk factors for root resorption of second molars with impacted third molars: a meta-analysis of CBCT studies

OBJECTIVE: The aim of this systematic review and meta-analysis is to identify the risk factors of external root resorption (ERR) on second molar (M2) due to presence of impacted third (M3) molar based on cone- beam computerised tomography (CBCT) findings. MATERIAL AND METHODS: MEDLINE, SCOPUS, and Experta Medical dataBASE (EMBASE) was performed to identify studies assessing the risk factors of ERR in M2 due to the presence of impacted M3. RESULTS: = .0003). Presence of the impacted M3 in the lower arch with ERR in M2 was higher (38.3%) than in the upper arch (33.8%). With respect to the inclination of impacted M3, the incidence of ERR was higher with transverse, horizontal and mesio-angular impacted M3 with 54.5%, 47.5% and 44.5% of occurrence, respectively. CONCLUSION: ERR in M2 was significantly affected by the contact with impacted M3 and most importantly, the inclination of M3. The presence of mesio-angular, horizontal or transverse impacted M3 in close proximity to apical or middle portion of M2 could possibly be a strong risk factor for ERR in M2.