The Anatomical Research on the Mental Foramen Related to the Mental Nerve Block

Objective: The aim of this study was to observe and investigate the location of mental foramen, providing scientific and reasonable anatomic basic for clinical mental nerve block. Methods: The shape, orientations, relationship with teeth and number of accessory mental foramina in 50 (100 side) adult mental foramina were observed. The long and short diameters of the mental foramen and the distance between the mental foramen and the peripheral anatomical markers were measured by a vernier caliper, and statistical analysis of the data was performed to obtain the final results. Results: The probability of mental foramen being elliptical in shape accounted for 27%, circular for 73%; 10% of the mental foramen openings are outward and 90% are outward and upward; The mental foramina were located under the first premolars in 20%, under the second premolars in 75%, and 5% situated in the bottom of the first molars. The incidence of accessory mental foramina was 1%; the long diameter of the mental foramen was (2.42 ± 0.71) mm, and the short diameter of the mental foramen was (2.15 ± 0.14) mm; the vertical distance from the mental foramen center to the alveolar crest and the lower margin of the mandible were (14.09 ± 3.23) mm and (14.56 ± 1.74) mm; the distance between the midpoints of the vertical line to the center of the mental foramen was (1.26 ± 0.97) mm; the horizontal distance from the center of the mental foramen to the anterior median line was (23.57 ± 1.82) mm. Conclusion: The point of mental nerve block was selected below and behind the second premolars, above the midline of the mandible. The distance from the anterior median line was 2.5 cm, and the mental foramen was explored forward and downward after the insertion.