Comparing the effect of pouring time and disinfection protocols of poly vinyl impression by autoclave and Ozone on its dimensional stability : In vitro study / Zeinab Saeed Alsayed Mohamed Alshamy ; Supervised Ahmed Hassanien , Rana Mahmoud Sherif

Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Prosthodontics

Purpose: to evaluate and compare the effect of autoclave and ozone disinfection protocols of poly vinyl siloxane (PVS) impression material on its dimensional stability after immediate and delayed pouring. Materials and Methods: Standardized stainless steel master model was constructed to simulate a fixed partial prosthesis with one pontic and two crowns in posterior area. Special trays were constructed to make impressions, 66 impressions taken and divided into 3 groups Group C: (GC) n=22 impressions (control), Group A: (GA) n=22 impressions disinfected by autoclave, Group O: (GO) n=22 impressions disinfected by ozone. Each group subdivided into two equal subgroups eleven each, subgroup (I) immediately poured and the subgroup (d) poured after 24 hours, all impressions were poured with type IV extra hard dental stone. Different dimensions were measured on cast. Result : There was statistical significant difference in mean values between (GC and GO), or (GC and GA) while there was high statistical significant difference in mean values between (GO and GA). Ozone and autoclave are considered an effective disinfection methods not adversely affect impressions dimensional stability if the impression poured immediately in case of ozone but delay pouring of impression for 24 hours in case of autoclave. Conclusion: PVS impression materials is dimensionally stable and produce accurate impressions with minimal distortion and the ability to retain these properties even after the disinfection procedures with autoclave and Ozone disinfection

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