Purpose of the study: The aim of the study is to analyze the way the disinfectants embedded in the plaster affect the setting linear dimensional stability, flexural and compressive strength of dental stone models. Material and Methods: Samples were made of type IV dental stone in which different disinfectants had been incorporated (sodium hypochlorite 1%, chlorhexidine 2%) in two concentrations (50%, 100%), thus obtaining four test groups. Mentioned parameters are measured using a micro comparison device and an universal testing machine, analyzing statistically the results in comparison with the control group, prepared by standard indications. Results: Disinfectants cause a decrease of the setting expansion value (ΔL) compared to the standard group in all type of mixing percentage. Variations of compressive and flexural strength are statistically significant, particularly when adding 100% of hypochlorite 1%. Conclusions: Within the limits of this study, replacing the distilled water with disinfectants, alter the value of setting expansion and cause the model dental stone to be brittle in compression and bending.