Comparison of dimensional accuracy of four different die materials before and after disinfection of the impression: an in vitro study.

BACKGROUND This study was conducted to compare the linear dimensional accuracy of die materials before and after disinfection of the impression. Type IV and V conventional dental stone, type IV-resin impregnated and copper-plated die materials were studied. MATERIALS AND METHODS A stainless-steel master die analogs to a complete veneer crown preparation with three scribed lines (I: vertical, II and III: horizontal) was machined and measurements were made from these scribed reference lines. Impressions were made with monophase addition silicone impression material for each of the specimens. 2% glutaraldehyde was used as a disinfectant. The fabricated dies were measured to the nearest 0.0001 mm. ANOVA and post hoc was carried out using Scheffe multiple comparison test at significance level of 0.05. RESULTS Type IV resin-impregnated dental stone and copperplated dies approximated the dimensions of the master die. Type IV and V conventional dental stone dies showed greater variation in measurements. Statistically significant differences were observed for type IV resin-impregnated and copper-plated dies in dimension I and III. For dimension II no significant differences were found for dies fabricated from four die materials. A one-way analysis of variance indicated no statistical significant differences among the two groups of dies fabricated from disinfectant treated impressions and those fabricated from nondisinfectant treated impressions. CONCLUSION Type IV resin-impregnated dental stone and copper-plated dies are dimensionally more accurate than type IV and V conventional dental stone die materials. No significant linear distortion in the dies fabricated from the disinfected impressions was observed.