義歯の適合を阻害する因子に関する基礎的研究

抄録

In order to improve the accuracy of the fit of resin dentures, several polymerization techniques have recently been introduced. It is important to know the best technique for processing to increase the accuracy of the fit. Thus, the linear shrinkage of resin specimen was examined during processing using specially designed oven and flask. In addition, the linear dimensional change and the vertical discrepancy of resin on metal models were also investigated and related with the amount of residual monomer included and water absorption. The results obtained were as follows : 1. The maximum temperature in polymerizing mass and the contraction during curing, in the case of experimental self-curing resin specimen, varied considerably from one flasking investment to another. And its temperature and contraction markedly increased with the rise in polymerization temperature and with the increase in monomer-polymer mixture quantity. 2. The polymerization shrinkage of self-curing resin was 74% of the whole curing shrinkage, and the thermal shrinkage of resin during cooling from the maximum temperature (75℃) to the room temperature (23℃) was 26%. 3. The magnitude of the dimensional change of self-curing resin specimen on the removal from the cast model was approximately 3∿5 times that of heat-curing one. 4. The quantity of residual monomer immediately after the curing process of self-curing resin specimen was 4∿6 times that of heat-curing one. 5. The elevation due to warpage of the dentures on the metal model decreased with the increase in water absorption and increased with the decrease in residual monomer. 6. When stored in water (37℃) for ten days after the curing, the water absorption of self-curing resin specimen was 1.5∿3 times that of heat-curing one. 7. The quantity of residual monomer of self-curing resin specimen decreased markedly when polished or thermal-cycled. 8. The accuracy of the resin specimen was markedly diminished by positioning the artificial teeth, especially porcelain ones, on the specimens, and/or by cooling rapidly after polimerization. Furthermore, its accuracy was also considerably deteriorated when the specimen was polished or thermal-cycled.