Morphological alterations in the position of the mandibular foramen in dentate and edentate mandibles

The technique of inferior alveolar nerve (IAN) block must be based on precise anatomical knowledge regarding the correct position of the mandibular foramen (MF). The aim of the investigation reported here was to determine the anatomic and topographic localization of the MF according to mandibular ramus anatomic landmarks and to identify morphological alterations in the position of the MF and size and shape of the ramus in terms of the impact of tooth socket loss in the molar and premolar region. Seventy-three dry human adult mandibles were divided into two groups according to dental status. These were measured to determine the distances from the anterior and posterior ramus border (AB, PB) to the midpoint of the MF fossa, and from the mandibular notch (MN) and inferior ramus border (IB) to the MF entering point. A number of relevant ramus anatomic features were analyzed, such as ramus width (RW), height (RH), and thickness (RT). The MF was closer to the PB and IB in edentate mandibles (right/left mean PB-MF 10.66 +/- 1.84/11.06 +/- 2.05 mm; right/left mean IB-MF 21.77 +/- 3.23/21.8 +/- 2.27 mm) compared to dentate mandibles (right/left mean PB-MF 11.87 +/- 2.08/12.04 +/- 1.94 mm; right/left mean IB-MF 22.94 +/- 3.09/22.74 +/- 3.74 mm). Edentate mandibles demonstrated reduced RW (right/left mean RW 26.03 +/- 3.53/26.49 +/- 3.90 mm), significantly reduced (p = 0.03) right RH (right/left mean RH 43.56 +/- 4.74/45.43 +/- 4.86 mm), and significantly reduced (p < 0.05) RT in the area of the MF fossa depression (right/left mean RT 5.52 +/- 1.21/5.21 +/- 0.91 mm) compared to dentate mandibles (right/left mean RW 27.34 +/- 3.84/27.48 +/- 3.80 mm; right/left mean RH 46.33 +/- 4.52/47.40 +/- 4.20 mm; right/left mean RT 7.86 +/- 1.98/8.10 +/- 1.92 mm). Alterations in MF position and mandibular ramus anatomic features in edentate mandibles increase the potential risk of complications and failure of IAN block.