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Important elements of chin anatomy
Medical expert of the article
Last reviewed: 04.07.2025
Although the basic anatomy of the mandible is well known to aesthetic surgeons, some points need to be emphasized. The position of the mental foramina is quite variable, but they are usually located below the second premolar. Anatomical studies show that in 50% of cases the mental foramina are located at the level of the second premolar, in 25% of cases they are located between the first and second premolars, and in the remaining 25% of cases they are located posterior to the second premolar.
In the mandible of a young person, the mental foramina are usually located midway between the alveolar ridge and the lower border of the jaw, approximately 25 mm lateral to the midline, although this distance may be from 20 to 30 mm. In children, they are located lower and anteriorly, and with aging, due to atrophy of the alveolar process, the mental foramina are closer to the alveolar ridge, maintaining a fairly constant distance from the lower border of the jaw.
That is, their relative position becomes higher. Even in the senile jaw, between the mental openings and the edge of the lower jaw, at the point of muscle attachment, a distance of more than 8 mm is maintained. The vascular-nerve bundle exits the mental opening upwards and is surrounded by a dense membrane.
The importance of the mental foramen anatomy in the aging mandible directly relates to the level of safety in surgical placement of mandibular augmentation implants. The anatomical features of this region clearly indicate that the surgeon should perform careful dissection, creating a pocket for the implant below the mental foramina but above the level of the muscle insertion along the inferior border of the jaw. Typically, 10 mm of space is available.
Correctly made implants should have a height of 6-8 mm in this area. Since the neuromuscular bundle is surrounded by a dense membrane and goes from the mental foramen upwards, using an elevator in the 8-10 mm space can affect the bundle and even stretch it somewhat, but it is very difficult to tear the bundle. Although this anatomical feature creates conditions for safe work, caution must be exercised when retracting the pocket wall.
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