Individual augmentation of the atrophic mandible based on CAD/CAM-manipulated computed tomography data--in vitro results.

The problems of shaping a stable alveolar ridge form favorable for prosthodontic treatment by the various methods of ridge augmentation raise the question of whether computer-aided design (CAD) may be used for geometric modeling of the implant. Helical computed tomography (CT) data were used to create a three-dimensional (3-D) model of the atrophic mandible. This numerically based model served as the basis for a free-form-surface design of the implant's form, height, and position. The idealized data required for this geometric modeling were also derived from numerically based serial sections of 104 mandibles of dried skulls. The modeling procedure followed the formula "idealized mandibular geometry minus patient's geometry", yielding the geometric data of the implant. These numerically control (NC) a milling machine to fabricate the individual implant. The augmentation of an atrophic mandible of a dried skull is presented as the first in vitro trial of this new method.