Geometric design method for class I inlay cavity.

The purpose of the present study was to establish a geometric design method for class I inlay cavities as a future method of computer-aided tooth preparation. Major occlusal fissures were used as a starting point of the cavity design and marked as multiple continuous line segments. An experimental cavity outline was defined by circular arcs and Bézier curves with three design parameters: minimum radius of curvature of the convex portion, taper angle of the convex portion of a cavity, and dovetail convexity angle. The experimental software was used to design class I inlay cavities for mandibular and maxillary right, first and second molars. Once the segments and the parameters were set, the outline was instantaneously drawn by the software. All design parameters worked as intended. Smooth class I inlay cavity outlines for molars with tool accessibility throughout the cavities could be obtained using the present design method.