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Linear dimensional accuracy of a polyvinyl siloxane of varying viscosities using different impression techniques
Sunil Mishra1, Ramesh Chowdhary
1Department of Maxillofacial Prosthodontics and Implantology, Dental College Azamgarh, Azamgarh, Uttar Pradesh, India.
Aim:
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.
Methods:
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.
Results:
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.
Conclusion:
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.
