Mohamed Sawi Mohamed, Nadia. A. Abbas And Mohamed. F. Abdallah,

ABSTRACT
AIM: In-vitro Study Was Carried-out To Compare The Dimensional Accuracy Of Three Different Viscosities Of Additional Elastomeric Polyvinyl Siloxane Impression Material (PVS)

Materials and Methods: Fabrication Of Custom Tray On Acrylic Model (Kennedy Class II Modification Then An Impression Was Made Using Three Deferent Viscosity Of Polyvinyl Siloxane Impression Material. The Impression Was Divided Into Four Groups. Group I: Impressions Using Light Polyvinyl Siloxane, Group II: Impression Using Medium Polyvinyl Siloxane, Group III: Impression Using Heavy Polyvinyl Siloxane, Group IV: Impression Using Three Viscosities In Single Impression. Finally Measurement From Acrylic Cast Was Recorded And Compared To That Measured From The Stone Cast Poured From The Different Viscosities Of The Impression Materials.

Results: When The Three Viscosities Used Together In The Same Tray They Produced Less Accurate Cast Than Medium Alone. However It Was More Accurate Than Light And Heavy Viscosities