The ultrasonographic determination of the position of the mental foramen in relation to hard and soft tissue landmarks in a selected South African black and Caucasian adult population
Background: Ultrasound can accurately locate the mental foramen and may facilitate local anaesthesia to the mental nerve under direct visualization. Methods: 100 subjects were included. An ultrasound transducer was used to locate the mental foramina. Distances to various landmarks were measured and compared. Results: All mental foramina were visualised. Overall the most frequent position of the mental foramen in relation to vertical hard tissue landmarks was in line with the long axis of the 2nd premolar tooth on the right and between 1st and 2nd premolar teeth on the left. There were no statistically significant differences between race groups, gender and age categories. The mean hard tissue distances from the mental foramen on the right and left sides respectively were as follows: a) 22.8 mm (SD 2.1 mm) and 22.8 mm (SD 2.0 mm) to the cusp of the related tooth. b) 13.2 mm (SD 1.6 mm) and 13.2 mm (SD 1.6 mm) to the inferior border of the mandible. The mean soft tissue distances from the mental foramen on the right and left sides respectively were as follows: a) 3.4 mm (SD 1.7 mm) and 3.4 mm (SD 1.5 mm) lateral to a vertical line passing through the chelion. b) 20.1 mm (SD 2.6 mm) and 20.1 mm (SD 2.6 mm) distal to a horizontal line bisecting the chelions. c) 15.1 mm (SD 3.4 mm) and 15.0 mm (SD 2.4 mm) to the inferior border of the mandible. Conclusion: Ultrasound is an effective modality to locate the mental foramen. There is insignificant variation in the position of the mental foramen in relation to v the mandibular premolar teeth between races. Statistically significant differences, for the distance of the mental foramen to various landmarks, were minimal and are not regarded clinically significant.
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg in partial fulfillment of the requirements for the degree of Master of Medicine (Emergency Medicine) Johannesburg, 2013