Influence of Repeat Pours of Addition Silicone Impressions on the Dimensional Accuracy of Casts

Aims and objectives: To evaluate and compare the time dependent dimensional accuracy of polyvinyl siloxane impressions. Materials and methods: A brass master die containing two identical posts simulating two complete crown tapered abutment preparation was served as a standardized master model. Impressions were made with polyvinyl siloxane materials (monophase and regular body) using a brass made custom tray. The impressions were repeatedly poured at 15 min, 75 min, 24 hours, 48 hours and 1 week., Interabutment and intraabutment distance were measured in the recovered stone dies (type iv, kalrock) using a profile projector with an accuracy of 0.001 mm. Results: Results of this study indicated that the casts made were dimensionally accurate and the polyvinyl siloxane silicones are dimensionally stable impressions for one week period. Conclusion: Repeated pouring of the impressions at the five different time periods did not significantly affect the accuracy of the casts produced.