THE EFFECT OF RESIDUAL STRESS AND WATER CHANGE ON THE DEFORMATION OF HYDROCOLLOID IMPRESSION MATERIALS

¹ Department of Dental Materials, Indiana University School of Dentistry, Indianapolis, Ind.

The water change in irreversible hydrocolloid impressions when stored in 3 different media was determined. The fluctuation in water content is slightly less in certain media than with reversible hydrocolloid. No significant difference was observed in water change of reversible hydrocolloid impressions when stored at various temperatures, except in 100 per cent humidity where storage at 98° F. increased imbibition.

Technics designed to increase the residual stress in reversible hydrocolloid impressions resulted in greater distortion, even though the water change was the same as in the control. These data suggest that release of internal stress may be of equal importance to water fluctuation during storage.