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

The aim of this study was to evaluate the dimensional accuracy of the recently introduced vinyl polysiloxane impression material "Express XT" when subjected to sprayed disinfection with cavicide1 disinfectant solution at two different pouring times. Using three dimensional DicoMesher software version3. A total of twenty impressions of a standardized stainless steel mold were made using express XT impression material in specially fabricated trays. The impressions were subjected to spray disinfection protocol using cavicide 1 disinfectant solution and then divided according to times of pouring into two groups immediate pour according to manufactures instructions and One-week delay pouring. Impressions were poured with a type IV extra hard dental stone. All measurements were performed on the photos of the produced cast by DicoMesher software a computer software program allowing three dimension recording. Results were statistically analyzed. Immediate pouring time showed the lowest mean overall dimensional changes while delayed pouring time showed higher mean shrinkage. However, there was no statistically significant difference between the overall dimensional changes of the two groups. Within the limitation of this study we concluded that different pouring times did not harm the dimensional stability of the die material

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