The position of the mental foramen in dentate and edentulous mandibles: clinical and surgical relevance.

BACKGROUND: The knowledge of the exact location of the mental foramen (MF) in dentate and edentulous mandibles is clinically important when constructing complete dentures, performing anaesthetic block of the lower-anterior teeth area and intervening in the MF nearby area. In edentulous mandibles, the bone resorption after teeth loss makes the mental nerve (MN) prone to damage due to the extreme location of the MF very close to the alveolar crest (AC). Chronic compression on the MN may result in pain in the area of MN distribution (ipsilateral face and cheek area) and numbness at the lower lip. The purpose of the current study is to evaluate the exact position of the MF, calculating the distances MF- superior border of the AC and MF- inferior border of the mandible (IBM) in dentate and edentulous mandibles.

MATERIALS AND METHODS: One hundred and two (36 edentulous and 66 dentate) adult dry Greek mandibles were studied.

RESULTS: In 9 out of 36 edentulous mandibles (25%), the MF was found nearby the AC, while in 27 edentulous mandibles (75%), the MF was located at an average distance 6.4 mm from the AC and 12.6 mm from the IBM. In 38 out of 66 dentate mandibles (57.6%), the MF was located at an average distance 13.6mm from the ALC and 15.2 mm from the IBM. The dental status significantly affected (p=0.001) the distances MF- AC and MF-IBM. Side symmetry was observed for both dentate and edentulous mandibles (p=0.39 and p=0.45).

CONCLUSIONS: The MF is an important landmark and its location needs to be considered prior to dental implants placement in order to avoid the MN injury and related complications. The position of MF is altered in edentulous mandibles compared with the dentate ones. The MF is a symmetric structure in Greeks.