The IAN is an important anatomical structure whose course affects the preoperative planning of a bone graft or implant insertion in the mandible. Knowledge on the bone thickness between the lateral wall of the mandibular canal and the lateral mandibular compact bone as well as of the position of the mental foramen facilitates decision-making [24]. Furthermore, for many other surgical procedures, the overall dimension of the mandible is crucial. This is the case in the removal of wisdom teeth, in the application of buccal mini screws for orthodontic anchorage and of course in orthognathic surgery [25,26,27]. Therefore, this study used CBCTs to assess the intraosseous course of the IAN, the bone thickness between the lateral wall of the mandibular canal and the buccal border of the mandibular cortical plate and the position of the mental foramen in relation to the neighbouring teeth. The findings were evaluated for men and women and different age groups, and both sides of the mandible were compared.

Analysing bone thickness, our CBCT-based study measured the distance between the mandibular canal and the buccal bone surface of the mandible. The measurement of other distances like, e.g. the length between the mandibular canal and the lingual, apical and cranial mandibular bone surface, was performed in various cadaver studies [28,29,30]. These studies show a 2.1–5.8-mm distance between the lingual bone surface to the mandibular canal, 8.2–21.3 mm for the upper border (alveolar crest) to the mandibular canal and 6.2–11.8 mm for the lower border to the mandibular canal as summarized by von Arx and Lozanoff [31]. Chrcanovic et al. performed preoperative measurements of the distances between the buccal and lingual bone surface to the mandibular canal using CBCTs, underlining the clinical relevance of the distance between the buccal wall and the mandibular canal due to an increased risk of nerve damage at short distances [32, 33].