Linear dimensional accuracy of a polyvinyl siloxane of varying viscosities using different impression techniques.

Abstract

The present study is an in vitro study to evaluate the linear dimensional accuracy of commercially available polyvinyl siloxanes of varying viscosities using different impression techniques. Different impression techniques used were: (a) putty wash, with a two-step technique with polyethylene spacer, using a stock tray; (b) putty wash, with a one-step technique, using a stock tray; (c) single-mix technique, utilizing medium viscosity in a custom tray; and (d) multiple-mix technique, utilizing a heavy- and low-viscosity combination in a custom tray. For each technique, 10 impressions were made of a metallic maxillary dentulous master model. The result of this study dictates that a heavy- and low-viscosity combination, double-mix technique in a custom tray produced an accurate result in all dimensions, followed by the single-mix technique, utilizing medium viscosity in a custom tray, and the putty wash two-step technique with polyethylene spacer, using a stock tray. Group 2 putty wash, one-step, simultaneous technique produced the least accurate result in all dimensions. The putty wash two-step techniques were found to be as accurate as the multiple-mix technique, utilizing a heavy- and low-viscosity combination in a custom tray, and the single-mix technique, utilizing medium viscosity in a custom tray. Making custom trays is time consuming and costly.