RESUMEN
OBJECTIVE: To evaluate the dimensional changes, reproduction of details, and surface roughness of a type IV cast and a resin used to fabricate dental models. MATERIALS AND METHODS: Two commercial brands of materials were evaluated: a type IV synthetic cast (Fuji Rock) and a polyol resin (Novox). Twenty samples were obtained from polyvinyl siloxane molds that reproduced the surface of a metal master model standardized according to the American National Standards Institute/American Dental Association specification no. 19. The materials were used according to the manufacturer's instructions and divided into two groups (n = 10). Each mold was photographed immediately after molding and 1 hour after molding. The obtained models were also photographed and measurements were obtained by using Image J software. The paired t-test was used to compare the molding materials and one-way analysis of variance (ANOVA) was used to compare the dimensional changes between the groups at a significance level of 5%. RESULTS: Statistically significant differences were observed between the models fabricated with the polyol resin and type IV synthetic cast with regard to reproduction of surface details, surface roughness, and dimensional stability (p < 0.05), with the resin providing superior surface detail reproduction and greater dimensional accuracy. CONCLUSION: The polyol resin exhibited superior behavior regarding detail reproduction, surface roughness, and dimensional change compared with the type IV synthetic cast.