External root resorption in maxillary and mandibular second molars associated with impacted third molars: a cone-beam computed tomographic study

Objective To separately investigate the prevalence and risk factors of external root resorption (ERR) in maxillary and mandibular second molars (M2s) adjacent to impacted third molars (M3s). Materials and methods CBCT scans involving 184 maxillary and 323 mandibular impacted M3s were included. Age, gender, the impaction status of M3, the presence, severity, and location of ERR in M2 were assessed. Risk factors were identified by multivariate logistic regression analyses. Results The prevalence of ERR was 32.6% in maxillary and 52.9% in mandibular M2s ( P