The mandibular canal is a bilateral, intraosseous opening through which the IAN runs from the mandibular foramen to the mental foramen. The nerve innervates the teeth, the mucous membranes in the area of the mental foramen and the skin around the chin [14, 15]. Anatomical variations of the mandibular canal, such as bifid canals and an anterior loop of the mental nerve, are common [16, 17] and have to be considered when planning surgical interventions (e.g. implantations, osteotomies) in the area of the mandible [14, 15, 18, 19]. The literature contains reports of sensory disturbances within the first 2 weeks after surgical interventions involving block harvests in up to 37% of patients, 10–15% of whom continue to have persisting complaints after 15 months [19, 20]. Other authors report milder complications after bone harvesting in the retromolar area of the mandible compared to the chin area [5, 12, 21,22,23].

The objective of this study was to evaluate the bone thickness between the lateral wall of the mandibular canal and the buccal side of the vestibular cortical plate of the mandible, i.e. the horizontal position of the mandibular canal, and to determine the position of the mental foramen in relation to the neighbouring teeth. The position of the mandibular canal is of particular interest in bone block harvesting in the posterior mandible, implant placement and root resection on mandibular premolars or molars. Preoperative three-dimensional diagnostics by CBCT is an essential planning tool to evaluate the donor region and was analysed in this study.