Anatomical relationship between mental foramen, mandibular teeth and risk of nerve injury with endodontic treatment.

OBJECTIVES: The objective of the present study was to evaluate the anatomical relationship between mental foramen (MF), including the incidence of the anterior loop of the inferior alveolar nerve (AL), and roots of mandibular teeth in relation to risk of nerve injury with endodontic treatment.

MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) images, which included teeth either side of the MF, were randomly selected. The anonymised CBCT images were reconstructed and examined in coronal, axial and sagittal planes, using three-dimensional viewing software, to determine the relationship and distance between MF and adjacent mandibular teeth. The actual distance between the root apex and MF was calculated mathematically using Pythagoras' theorem. If present, the incidence of an AL in the axial plane was also recorded.

RESULTS: The root apex of the mandibular second premolar (70 %), followed by the first premolar (18 %) and then the first molar (12 %), was the closest to the MF. Ninety-six percent of root apices evaluated were >3 mm from the MF. An AL was present in 88 % of the cases.

CONCLUSIONS: With regards to endodontic treatment, the risk of nerve injury in the vicinity of the MF would appear to be low. However, the high incidence of the AL highlights the need for clinicians to be aware and careful of this important anatomical feature.

CLINICAL RELEVANCE: The risk of injury to the MN with endodontic treatment would appear to be low, but given the high incidence, it is important to be aware and be careful of the AL.