Comparison of Repeated Chemical and Microwave Disinfection on Compressive Strength of Gypsum Casts - An In Vitro Study

Objectives: The aim of this study was to compare two disinfection methods (microwavedisinfection and chemical immersion disinfection) and to determine the best disinfectionmethod for the gypsum cast which produce the least changes on compressive strength.Materials and Methods: A total of 36 specimens were prepared using standardized carbonsteel dies. The specimens were divided into three groups (n=12 each): Control groupcontains gypsum rinsed with distilled water, Study group I consists of gypsum castsimmersed in 0.5% Sodium Hypochlorite and Study group II consists of gypsum castsirradiated in a microwave oven. Compressive strength of the specimens was evaluated usinga universal testing machine, where each specimen was placed on the test platform andcompressed to record the deformation at various loads.Results:In this study, the mean compressive strength values obtained were 24.69 MPa forGroup 1, 13.77 MPa for Group 2, and 23.93 MPa for Group 3. Statistical evaluation showeda significant variation among the groups, with Group 2 exhibiting considerably lowercompressive strength than Groups 1 and 3.Conclusion:Based on the findings, it can be concluded that immersion in sodiumhypochlorite significantly reduces the compressive strength of the tested material, whereasmicrowave disinfection does not cause a notable decrease compared to the control.Keywords: Gypsum; Compressive strength; Chemical disinfection; Microwave disinfection.