1997 Volume 16 Issue 2 Pages 180-190,225
To analyze the functional and morphological harmonies of the tooth and dental arch, a computerized system to measure a dental cast and to detect the apex of dental cusps and angle points of incisors was developed. Detailed morphology in the measured dental cast could be displayed distinctively by computer graphics (CG) with a surface model.
Accuracy in determining the position of the apex of the dental cusp was examined by increasing the measuring pitch from 50μm to 400μm, the error increased gradually with increased measuring pitch. Taking the measuring error, the time for measurement and the memory size for analysis into account, a measuring pitch of 200μm was determined to be reasonable.
Three-dimensional data measurements from the apex of the dental cusp in molar, and the mesial and distal angles in canine and incisor were fitted to a polynomial formula. In the present measured model, the 4th order polynomial formula was used for the dental arch, and the 2nd order polynomial formula was used for the anteroposterior and lateral occlusal curves. These formulae could be simultaneously superimposed on the surface model of the dental cast, and displayed using CG.