印象法の違いが作業模型の寸法精度に及ぼす影響について

Abstract

The purpose of this study was to evaluate the impression techniques for polyvinyl siloxane impression materials in terms of the accuracy of the resultant stone casts. An acrylic resin maxillary model with nature dentition was prepared as the original model. Four impression techniques with or without undercut blockout were selected to make the impressions, using stock tray only, custom tray only, custom tray with resin copings for abutment teeth and custom tray with bridge copings. The dimensional changes of the anterior bridge area and posterior bridge area of stone casts were compared. The results obtained were as follows : 1. The effect of undercut blockout on the accuracy of stone cast was more significant in the anterior bridge area than in the posterior bridge area. 2. The dimensional changes of the anterior abutment teeth were more significantly affected by the impression techniques than those of the posterior. 3. It would appear from this study that the impressions made by custom tray with bridge coping were superior to those by the other techniques in terms of the dimensional accuracy and stability of the stone casts.