Dimensional Accuracy of 7 Die Materials

Purpose: The purpose of this study was to compare the linear dimensional accuracy and the handling characteristics of 7 die materials. Materials and Methods: A master die analogous to a complete veneer crown preparation was machined from medical grade stainless steel, and 3 measurements (1: vertical; 2 and 3: horizontal) were made from 3 scribed reference lines. Individual polyvinylsiloxane impressions were made (n = 10) for each of the specimens. The fabricated dies were measured (50×) to the nearest 0.0001 mm. Data were subject to ANOVA/Duncan tests at significance level 0.05 and pairwise comparisons. Results: Type IV resin‐impregnated dental stone and copper‐plated dies most closely approximated the dimensions of the master die, and were not significantly different from each other in any of the pairwise comparisons. Conventional Types IV and V dental stone dies exhibited setting expansion within the range appropriate for gypsum. Epoxy resin die materials demonstrated shrinkage comparable to the expansion of the Types IV and V dies. Polyurethane dies displayed a combination of linear expansion and shrinkage. Bis‐acryl composite resin dies had excessive shrinkage. Conclusions: Type IV resin‐impregnated dental stone and copper‐plated dies were more dimensionally accurate than the other die materials tested.