Evaluation of Risk Factors for External Root Resorption and Dental Caries of Second Molars Associated with Impacted Third Molars

Abstract Purpose Impacted third molars (M3s) may lead to external root resorption (ERR) and dental caries (DCs) in the adjacent second molars (M2s). The aim of this study was to identify the risk factors for ERR and DC of M2s associated with impacted M3s. Materials and Methods The investigators implemented a cross-sectional study and enrolled a sample composed of subjects with M3s and M2s present and CBCTs available for review. If there was a contact between M2 and the adjacent M3 and the border of radiolucency was more distinct, this case was considered as ERR. Apart from that, other cases were considered as DC. Potential predictor variables were defined as age, sex, tooth number, M2/M3 contact, root development in M3, M3 inclination, M3 impaction type and M3 follicle diameter. Outcomes of the study were DCs and ERR of M2s. CBCT was used to detect the presence of DC and ERR on the M2. Results Total of 250 eligible images of M3 in upper and lower jaws of 167 patients were included. The mean age of the patients having CBCT images was 26.08±4 (range: 18 to 40) years and 43.6% of the patients were male. Factors associated with a significantly increased frequency of ERR in M2 included maxillary location, the presence of M2/M3 contact and mesioangular inclination (p Conclusion The results of this study demonstrated an increased risk for ERR were associated with maxillary molars, mesioangular inclination and presence of M2/M3 contact. The variable associated with an increased risk for DCs was the absence of M2/M3 contact.