Purpose: To evaluate the surface roughness and dimensional stability of types III and IV gypsum models, obtained from irreversible hydrocolloid impressions after disinfection with 5.25% sodium hypochlorite steam.
Methods: The impressions to obtain type III and type IV gypsum models were divided into 3 groups: Group 1 (disinfection with 5.25% sodium hypochlorite steam for 10 minutes); Group 2 (simulated disinfection with distilled water steam) and Group 3 (no treatment). To measure the dimensional changes with a digital caliper, 36 models (18 for each type of gypsum) were cast according to a stainless steel master model with four pillars. For the surface roughness measurement, 36 gypsum models were cast from the impressions of the polished stainless steel platform. The data were analyzed using ANOVA and Tukey’s test (α=1%).
Results: There was no statistically significant difference in linear dimensions or surface roughness when the different disinfection treatments were compared (Groups 1, 2 and 3), for all types of gypsum.
Conclusion: The disinfection treatments with sodium hypochlorite steam and distilled water steam for irreversible hydrocolloid impressions did not significantly affect the dimensional stability and surface roughness of the types III and IV gypsum dental models.