ObjectiveTo study the influence of four different disinfection methods on the physical indicators of dental stone casts. Method(1) After making a metal model imitating the rigid fixe d bridge, 25 plaster models were reproduced using alginate impression material, which were randomly divided into 5 groups, five in each group. A group was used for blank control, B group received ultraviolet disinfection, C group received high pressure steam sterilization, D group received microwave sterilization, E group received formaldehyde fumigation. The processed dimensional accuracy of plaster models were measured. (2) 25 rectangular plaster models were perfused using a standard rectangle selfmade curing resin mold, 50 mm×10 mm×5 mm in size, followed by grouping and disinfection by following the same steps mentioned above. The surface hardness were determined. Results(1) The dimensional accuracy of the plaster models before and after four kinds of dis infection methods showed no significant changes(P＞0.05).(2) Both ultraviolet disinfection and formaldehyde fumigation did not affect the surface hardness of plaster models(P＞0.05).(3)High pressure steam sterilization and microwave sterilization significantly affected the surface hardness of plaster models (P＜0.05). Conclusion(1)Four disinfection methods do not influence the dimensional accuracy of plaster models.(2)High pressure steam sterilization can decrease the surface hardness of plaster models, while microwave sterilization can increase the surface hardness of plaster models.(3)Disinfection using microwave sterilization is suitable for clinical gypsum model

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