Designing a transmandibular implant with the aid of biostereometric analysis.

A biostereometric survey of severely resorbed dry mandibles was used to determine whether it was possible to design a transmandibular implant that could be used for the majority of clinical situations. Computerized profiles of the relevant mandibular areas were generated and superimposed to examine the feasibility of a universal shape. It would appear that the crestal shape of the mandible between the mental foramina is on the circumference of a circle and that the surface of the inferior border is so variable that a flat surface would have to be used for a transmandibular implant. A design of a transmandibular implant is proposed on the basis of the common anatomic features of the mandible.