[Influence on the movement of a complete denture caused by differences in artificial tooth materials].

An experiment using modal analysis was used to ascertain the activity of complete dentures and artificial teeth. Three types of artificial teeth were used: a porcelain tooth, a resin tooth and a hard resin tooth. Animation and displacement values were used as criteria in determining the influence that differences in tooth materials had on the activity of the complete denture. The experiment was conducted to act as an aid in denture design and the following results were obtained: 1. The resonance frequency for the different test materials ranged from mode 4 to mode 7. 2. Regarding displacement value, a value of 1 micron or more was obtained in the 1 octave bandwidth for the 250 Hz band, 500 Hz band and the 1 kHz band. Among these, maximum displacement for the upper complete denture was as follows: When a porcelain tooth was used and a vibration of 1 for mode 1 (197 Hz) was applied, the value for the 3 cusp tip was 39.48 microns and that for the labial denture border side was 43.35 microns. As for the lower complete denture, when a porcelain tooth was used and 5 oscillation was applied for mode 1 (309 Hz), the value for the 3 cusp tip was 68.38 microns and that for the rear part of the denture border was 139.2 microns. 3. Regarding the activity of the complete denture in the 250 Hz and 1 kHz bands, when a porcelain tooth was used, a curve mode was observed for the upper complete denture in the labiolingual direction with the cervical line as the border. When the resin tooth and hard resin tooth were used, it was difficult to recognize any change with the cervical line as the border. It was also difficult to recognize a change at the cervical section for the lower complete denture. 4. As for the 500 Hz band, when a porcelain tooth and a resin tooth were used, there were frequencies (300 Hz-400 Hz) at which twisting in a labiolingual direction at the cervical section was recognized for the upper complete denture as well as frequencies (400 Hz-600 Hz) where this was not recognized. A rigid body mode was recognized when the hard resin tooth was used. In addition, differences in the location for applying for vibration had an influence on the activity of the lower complete denture.