Prevalence of retromolar canal and foramen: A cone beam computed tomography study

Introduction: The retromolar fossa is a triangular area posterior to the third mandibular tooth. An opening called the retromolar foramen (RMF) and a canal called retromolar canal (RMC) are known to be present in this area. The RMF is an anatomical structure on the alveolar surface of the retromolar triangle. The contents of the RMC have been reported to consist of branches of the inferior alveolar vessels and nerves. Retromolar area is related to surgical procedures that may lead to unexpected bleeding or paresthesia. Aims and Objectives: (1) To determine the prevalence of RMF and RMC in the mandible using cone-beam computed tomography (CBCT). (2) To observe variations, if any, in the appearance of the same. (3) To determine the length of the RMC, diameter of RMF, and proximity (distance) of the RMF from the cementoenamel junction (CEJ) of the mandibular molars. (4) To propose a classification for the presentation of the RMC. Materials and Methods: A retrospective analysis was carried out for the presence and characteristics of the RMC and RMF. The retromolar region of the mandible on both sides (right and left) was examined in 80 CBCT scans (N = 80). Results: The RMCs traversed in different directions – horizontal, vertical, and angular. Based on a subjective assessment, each of these canals was further subclassified into either a straight or curved canal. In the present study, RMF was found in 3 cases unilaterally (3.8%), out of which 2 were males (2.5%) and 1 was female (1.2%), and distance from the midpoint of the same to the CEJ of first, second, and third molars were determined. Conclusion: The prevalence of RMC and RMF showed that all RMC may or may not end into RMF. The three different varieties of RMC observed were classified into horizontal, vertical, and angular typeswhich were further subclassified based on a subjective assessment of each of these into either a straight or a curved canal.