抄録
I investigated how to reduce the time required for occlusal equilibration of prostheses in daily clinical practice by carrying out experiments on the precision of the opposing model. I measured variations in the dimensions of models that were fabricated when various conditions were changed, such as the water-to-powder ratio of the alginate impression material, the pressure applied to the impression tray during setting of the impression material, and the water-to-powder ratio of the plaster. In addition, I compared these values with those obtained for plaster models fabricated using the standard water-to-powder ratio, and investigated variations in products.
I concluded that precision was best when less water was mixed into the alginate impression material. Furthermore, it seems advantageous to reduce the amount of water when mixing the plaster since this increases the strength, while at the same time causing no problems with precision. For this reason, and because experiments have shown that different lot numbers of plaster require different water-to-powder ratios, I concluded that it is necessary to reconsider the concept of a standard water-to-powder ratio.
