Abstract
Attempts have been made to apply advanced CAD/CAM technology to the design and manufacturing of dental prostheses such as crowns and bridges in order to simplify production procedure as well as to improve their quality. Presently, several dental CAD/CAM systems capable of designing occlusal surface are available commercially. Design of complicated occlusal surfaces is of primary importance in dental CAD, due to its function in patient's stomatognathic system. In particular, location of contact points in the intercuspal position is essential to obtain a functional occlusal surface without interference. Previous interfere-free design, however, has been done on a trial-and-error basis by using visual inspection. In order to improve such time-consuming and inaccurate procedure into a semi-automatic and accurate one based on quantitative evaluations, we already developed two difference functions for dental CAD system such as 1) a virtual dental articulator, and 2) proximity mapping on the crown surface relative to its opposing occlusal surface. Subsequently, this paper proposes a computer-aided system for assisting the determination of occlusal contact points employing the proximity mapping on the opposing surface. The system can designate such regions, which can be estimated from contour of the opposing occlusal surfaces and their relative movements simulated by using the virtual articulator. In an attempt to evaluate applicability of our system, several experiments for designing the crown of a lower first molar were carried out using three different types of opposing teeth with different cusp angles. The results demonstrated that all contact points located within the designated regions completely satisfied the required conditions regarding contact and separation during every tooth excursion. It is strongly suggesting that our assisting system has wide range of clinical applicability.
