OBJECTIVE To study the influence of three kinds of disinfection methods on surface hardness of oral gypsum casts.METHODS The metal cylinder mould and silicone impression was made.Three kinds of gypsum casts including plaster,dental stone,and high strength dental stone were made and disinfected by three kinds of disinfection methods,which were microwave heating,high temperature and pressure and ultraviolet radiation disinfection.After disinfection,the surface hardness was tested and the statistical analysis ...