In vitro Comparison of Dimensional Stability of Stone Dies Obtained from Two Elastomers after Two Treatments

Abstract

ABSTRACT Aim The aim of the study was to compare the dimensional stability of dies obtained from addition silicone and polyether impressions that were reheated or subjected to vacuum treatment. Materials and methods A master die was constructed of a rectangular stainless steel block on to which a photosensitive nylon printing plate attached which contains engraved test grooves. A custom-tray was fabricated and impressions were made using addition silicone and polyether before and after the two treatments. A total of 90 impressions and dies were made from both the elastomers and divided as control group, group I (reheated impressions) and group II (vacuum-treated impressions). A comparative analysis was done to determine which dies yielded the best dimensional accuracy compared to that of the master die. Results The minimum percentage dimensional change was observed in test dies made from addition silicone impressions of group I (reheated impressions), followed by the test dies made from polyether impressions in control group. The maximum percentage dimensional change was observed in test dies made from polyether impressions in group I (reheated impressions), followed by the test dies made from addition silicone impressions in group II (vacuum-treated impressions). Conclusion The dies obtained from reheated addition silicone impressions yielded the best dimensional stability overall when compared with that of the master die. The dies made of polyether impressions after reheating were not clinically acceptable, because of its hydrophilic nature swelled when they were reheated in a water bath.