The Comparison Flow of Four Impression Compounds (Green Stick) with ADA Standard

Statement of Problem: Low- fusing compound (type 1) is used for border molding and impressions. Flow and reproducibility of surface detail are two important characteristics of these materials. There are no valid data available comparing domestic and imported brands. Purpose: The Purpose of this study was to evaluate these two properties of four different products including Kerr (Kerr Manufacture MI 98174-2600), Harvard (Hoffman Harvard Dental GMb H Germany); Kymia (Kymia dental company 713 Iran); and Pishro (Pishro 72534 Iran). Materials and Methods: All procedures were followed according to ADA and BS-Standard. Total number of 48 samples were divided into 8 groups (6 in each group). Twenty disks were fabricated for impression tests. The specimen dimensions were 40 mm (diameter) and 6mm (thickness). Standard test blocks were used to test the specimens. Results: The Willcoxon test showed significant difference in flow rate between materials tested with the best result for Kerr (P<0.05). Kerr flow was 85% and under 5% at 45°C and 37°C, respectively. There were great deviations from standards value at 45°C. For the rest of the samples at 37°C; except Kymia the flow rate for 3 materials (Kerr; Harvard Pishro) were almost acceptable. The impression test results revealed that only Kerr was able to record the details at 45°C. Conclusion: Kerr flow is exactly what ADA standards specify. But the flow rate for three materials exhibit a great distance from these standards. In impression test only Kerr was able to record the details