ABSTRACT
We compared the usefulness of 3-D plastic models with that of 3-D CT images with regard to their applications in the field of maxillo-facial medicine. We also considered possibilities for wider clinical applications for both these methods. Five patients with the following conditions were involved in this study: hyperplasia of the mandibular condyle, 1; fracture of the maxilla and mandible, 1; coronoid hyperplasia, 2; and unilateral temporomandibular joint ankylosis with microgenia, 1) Stereolithographic models and 3-D CT images were made for each patient. Ct and 3-D CT images were superior to plastic models with respect to their clinical diagnostic value. Furthermore they provided more precise information about the surface and inner structures of the jaws. 3-D plastic models made it possible to do close observation of the complex anatomical relationship of the region which were easily overlooked on axial CT images and even on 3-D CT images. The 3-D plastic models were useful for simulated surgery in all these cases. In the cases with bilateral coronold process hyperplasia, the plastic model well clarified the direct functional cause of the patients trismus. The analysis on plastic models suggested that the abnormal contact of the coronold process with the deformed surrounding anatomical structures might cause trismus and elongation of the process. We believe that plastic models can be applied to other dental fields such as dental implantology, prosthodontics and measuring for 3-D cephalometry