Relationship between Root Apices and the Mandibular Canal: A Cone-beam Computed Tomographic Analysis in a German Population

Introduction: The purpose of this study was to assess the mean distance between the mandibular canal and the apices of the adjacent teeth. Methods: Six hundred twenty-seven full-size cone-beam computed tomographic radiographs (Planmeca Promax3D; Planmeca, Helsinki, Finland; volume 8 x 8cm, voxel size mm) of a German population (female = 58.2%, male = 41.8%, mean age = 51 years) were analyzed to establish the shortest distance between the mandibular canal and the root apices of the second premolar and all molars using the multiplanar reconstruction of the manufacturer's software in 3 mutually orthogonal planes. The obtained metric data were statistically analyzed using Student-Neumann-Keuls and Scheffe tests. Concerning the position of the tooth, the left or right side, and the sex of the patients, the chi-square test was used. Results: A total of 821 second mandibular premolars and 597 first, 508 second, and 48 third mandibular molars were included, and the mean distances were 4.2, 4.9, 3.1, and 2.6 mm, respectively. The occurrence of a direct relationship between the root tips and the mandibular canal was found in 3.2%, 2.9%, 15.2%, and 31.3% of the teeth. Women were almost twice as often affected as men. No significant differences were found concerning the location (right/left) of the teeth (P > .05). Significantly shorter distances from the mandibular canal to the root apices were found in patients younger than 35 years compared with older patients (P < .0012). Conclusions: Direct communication between the root apices and the mandibular canal is not rare and has to be taken into consideration when performing surgical or endodontic procedures to avoid iatrogenic nerve damages. Distances depend on sex and age.