A Study on Dimensional Stability of Cold-curing Pattern Resins

Abstract

Four commercial cold-curing resins including three pattern resins (G.C Pattern Resin, Product D, and Product P) and one repair resin (G.C Uni-Fast) were subjected to dimensional stability test. The problems of dimensional accuracy of cold-curing resin is two-fold. It depends upon the amount of setting shrinkage and duration of setting (complete setting time) .
The purpose of this study was to determine complete setting time when resin does not show any dimensional change and to measure the amount of distortion during setting. The results may be summarized as follows:
1. Different amount of shrinkage was observed between two tests. Dimensional change of the resin in oral condition (37°C) was approximately 0.08% greater than that in ambient condition (23°C) . This difference may be due to the effect of thermal shrinkage.
2. Shrinkage of the resin was observed after removing a set pattern from a mold. This may be caused by relaxation of internal stress.
3. The complete setting times in ambient condition (23°C) and oral condition (37°C) were determined for each of the resins. In ambient condition, G.C Pattern-Resin sets completely in about 15 minutes and others set in 60 minutes. In oral condition, G.C Pattern Resin sets completely in 10 minutes and others set in 30 minutes.
It is concluded in this study that the G.C Pattern Resin sets in the shortest time with the least amount of shrinkage among the resins tested. Thus, G.C Pattern Resin may be effectively applied for the fixation of assembled parts of prosthetic appliances and the fabrication of resin crasp patterns and resin copings for removable partial denture frame.