Cone beam computed tomography-anatomic analysis of mandibular posterior teeth: impact on endodontic microsurgery

Abstract

Purpose: The purpose of this study was to use cone beam computed tomography (CBCT) measurements to investigate the root thickness (B-L) of the mandibular posterior teeth at the root end resection level, the thickness of the buccal and lingual bone at both the resection level and the mandibular canal (MC) level, the dimension of the mandibular canal, the relative location of the mandibular canal to the tooth, and the possible differences between males and females.Methods: CBCT scans from 106 patients were used to evaluate measurements from 801 teeth and respective tooth areas. Bone and root thickness were measured at the preferred root resection level of 3mm from root apex, and at the level of the mandibular canal. Also, the dimension and the relative location of the mandibular canal (MC) to the apices of the posterior teeth were evaluated. Results: Buccal bone was thinnest over the root of the 1st premolar (2.08 mm) and thickest over the distal root of the 2nd molar (6.35 mm). Bone thickness averaged 2.19 mm over the root of the 2nd premolar, 2.3 mm over the mesial root of the 1st molar, 3 mm over the distal root of the 1st molar, and 5.16 mm over the mesial root of the 2nd molar, respectively. Root thickness (B-L) at the resection level averaged 4.58mm, 5.42mm, 5.28mm, 5.77mm, 4.39 mm and 4.3mm for the 2nd molar distal root, 2nd molar mesial root, 1st molar distal root, 1st molar mesial root, 2nd premolar and 1st premolar, respectively. Mandibular bone thickness lingual to the root was more consistent, ranging from the thinnest area over the distal root of the 2nd molar (2.42 mm) to the thickest over the root of the 2nd premolar (4.5mm). The mandibular canal (MC) location in relation to the individual tooth roots was most often seen to the buccal in the area of the 2nd molar distal root (58%) while it was most often seen to the lingual of the root at the level of the mesial root of the 1st molar (31.5%). The MC was inferior to roots of posterior teeth in 38-58% of the time. Conclusions: Knowledge of the mandibular posterior tooth dimension for apical resection is beneficial to the endodontist. The depth of the root below buccal bone, its relative position in the mandible as well as to the mandibular canal can aid the surgeon performing the root resection and this data contributes to a knowledge base for the practicing endodontist.