Bilateral absence of mental foramen in a living human subject.

The mental foramen, through which the mental nerve emerges, is an important anatomic landmark in odonto-stomatology. Knowing its anatomic variations, according to the ethnic group or age, is essential when performing local anesthesia or implant and orthognathic surgeries. Besides the presence of a supernumerary foramen and variations in its location, numerous topographies have been described such as unilateral or bilateral triple foramina, hypoplasia or agenesis.