The Incidence of Mandibular Second Molar Distal Caries Associated with Impacted Mandibular Third Molar: A Retrospective Study and Management Guidelines

One of the notable complications of impacted mandibular third molar (MTM) is distal caries of the mandibular second molar (MSM) which can eventually lead to its early loss. The present study aimed to investigate the incidence of dental caries in MSM associated with impacted MTM and to propose an assessment protocol for MTM management. Patients’ dental records with dental panoramic tomography (DPT) imaging were studied retrospectively, in total 583 MTM images were evaluated. The presence of MSM distal caries, patient’s details, impaction depth, pattern and angulation of MTM and the distances between distal MSM and mesial MTM were assessed. Logistic regression analysis was performed on the data set. The highest caries incidence was observed in mesioangular impacted MTM (34.1%). Majority of the caries found were Level A (27.9%) and Class II (27.0%). The highest distance between distal MSM and MTM contributing to caries was 0.70-0.99 cm (31.9%). Patients’ age, angulation, pattern and depth of impacted MTM are the predictors which significantly increase the caries incidence in MSM (p<0.05).  Prophylactic removal of MTM should be proposed when the distance of mesial impacted MTM and distal MSM is around 0.70-0.99 cm, and is mesially angulated with IIA classification.