Inferior alveolar nerve topography and its bifurcation features: a cone beam computed tomography evaluation.

Background: Mandibular canal (MC) is the most important vital structure in mandible to prevent from complications such as bleeding and paresthesia. The aims of the present study were to inform the features (diameter, distances to the mandibular borders, and distance to tooth apex) of the MC for each posterior tooth region, and to present the bifurcation features of the MC.

Methods: Four-hundreds-eighteen MC images of 209 patients were evaluated. The parameters were recorded from right and left hemi-mandibles for each posterior teeth region: 1) MC diameter; 2) MC and mandibular basis distance; 3) MC and crest distance; 4) MC and tooth apex distance; 5) MC and buccal plate distance; 6) MC and lingual plate distance; and 7) possible implant length (the distance between 2 mm coronal of the MC and 1 mm apical of the crest). Additionally, MC bifurcation type and bifid mandibular canal length were noted for right and left sides.

Results: While higher MC diameter values were recorded at molars, MC diameter in first premolars bilaterally were the lowest. In premolars, MC and mandibular basis distance showed higher values than molars. There was a trend of decrease in MC and crest distance from molars to premolars. The highest MC and tooth apex distance was measured in second molar; however, the lowest was in the first premolar. Additionally, MC and buccal plate distances were higher in molars, while MC and lingual plate distances were higher in premolars. Possible implant length in first premolar was the lowest, when it was the highest in second molars.

Conclusions: For simulating overall MC topography, it extended bucco-coronally from molars to premolars. Due to this topography, possible implant length increased from premolars to molars.