遊離端義歯の維持歯歯根部に加わる曲げ応力

Abstract

The artificial posterior teeth of the free-end saddle denture directly transmit through food the masticatory force to the denture base during mastication. A grasp of the occlusal surface form and functions of the artificial posterior teeth is therefore essential in containing the effects of the denture on the circumferential tissues within the physiological limits. Clinical selection and arrangement, however, of the artificial posterior teeth are often made on the basis of the past experiences, and the standards for selection are quite indefinite. Therefore, unilateral free-end saddle denture models of cantilever type were prepared with the artificial posterior teeth set for two and the changes in the effects on the anchor teeth roots with a change in occlusal surface form were measured quantitatively. Five different simulated models of occlusal surface form of the artificial posterior teeth were prepared for the experiment : 0°(10mmφ), 20°(10mmφ), 30°(10mmφ), 0°(6mmφ), 45°(6mmφ). However, the occlusal surface form of the anchor teeth was set for 0°(10mmφ) for all cases. The results obtained were as follows : 1. In the case of the unilateral free-end saddle denture, increasing the number of the anchor tooth from one to two reduced the burden on the distal anchor tooth to as little as 6-7%. 2. Arranging the artificial posterior teeth distally increased the burden on the anchor teeth. 3. When the artificial posterior teeth portion was loaded in the case of two anchor teeth, the load distribution was constantly about 40% on the mesial anchor tooth root and about 60% on the distal one. 4. In any range of the distributed load, from the model anchor tooth (α) to the model artificial tooth (δ), from the model anchor tooth (β) to the model artificial tooth (δ) and on the model artificial teeth (γ) (δ) alone, the trend of the burden on the anchor teeth was the same as that under concentrated load. 5. Of the artificial posterior teeth of the unilateral free-end saddle denture, cusp teeth exerted less burden on the anchor teeth than cuspless teeth.