[Effect of the resin-bonded restorations on the tooth displacement and the loading force of the supporting tissues]

A mechanical simulation model of tooth and alveolar bone was made and analyzed using three-dimensional finite element technique. And the variations of tooth mobility and the periodontium supporting force caused by the absorption of alveolar bone was investigated. The results obtained were as follows: 1. When the physiological tooth mobility was 150 microns, the teeth were sufficiently fixed using the resin-bonded splint and bridge connected with more than three teeth in the case of 40 percent of alveolar bone absorption. However in the case of 60 percent of alveolar bone absorption, the teeth were not fixed with splint and bridge of six teeth connections. 2. In the application of resin-bonded splint and bridge, when the metal frame thickness was 0.5 mm, the effect of the connected place on tooth mobility was large, and the abutment teeth were sufficiently fixed when the abutment teeth were connected up to the neck. 3. The periodontium supporting force decreased markedly according to the increase of abutment teeth. 4. When the abutment teeth were less than five teeth, the inhibitory action for tooth mobility of the resin-bonded splint and bridge was widely different, and resin-bonded splint was more effective compared with bridge.