Abstract: Objective To investigate the dimension changes of plaster casts after impression disinfection with various disinfection methods.Methods 54 alginate impressions were made according to a standard model and disinfected with 1〖JP20〗∶〖JP〗100 chlorine containing disinfectant,2% glutaraldehyde disinfection solution and the running water (control group),respectively.Then cast pouring was done to the 54 impressions respectively with ordinary gypsum,anhydrite and super hard plaster.The dimensions of specific positions of the plaster casts were measured and compared with those of the standard model.Twoway ANOVA and Tukey HSD were performed with SPSS 17.0 statistical software.Results After disinfection,the dimensions of the plaster casts were smaller than the standard one; the dimensions of the ordinary gypsum group were close to the standard model.With the same disinfection method,the dimensions of the super hard plaster in glutaral disinfectant group were larger than those of the anhydrite dimensions.In the chlorine group and the control group,the largest was ordinary gypsum,followed by anhydrite and super hard plaster.Statistical analysis showed that cast dimensions were not affected by disinfectant methods,but by various model materials.The largest dimension change was -0.71 mm.Conclusions Chlorine disinfectant and glutaral disinfectant have no significant effect on dimensions of plaster models.

Key words: impression, model, dimensional change, disinfect