A Three-dimensional Study of the Reproducibility of Stone Casts obtained from Alginate Impressions : Part I:Effects of Temperature during Setting, Storage Environment and Storage Time of Impressions on Dimensional Accuracy

Abstract

The reproducibility of sylindrical stone casts obtained from two types of alginate impression materials was evaluated according to the temperature during setting(23℃ and 32℃), storage environment(in air of 50% and 100% relative humidity and in water)and storage time(0, 15 and 60 minutes)of impressions using a three-dimensional measuring system.The three-dimensional accuracy of the cast was affected by the type of impression material.The diameter of the cast became smaller as the degree of hygroscopic expansion of impression was larger when the stone was poured without storage.Thermal shrinkage had no effect on the dimensional change of the cast.The effects of the duration and environment of impression storage appeared as coresponding changes in directions opposite to the dimensional change of the impression materials.