Tear Strength of Four Irreversible Hydrocolloid Impression Materials

Purpose The purpose of this investigation was to examine the tear strength of four irreversible hydrocolloid (alginate) impression materials (Tare-Free Alg, Jeltrate, Identic, and Kromopan). Materials and Methods Eighty specimens, 20 for each alginate tested, were according to the manufacturers' instructions. A cutting die described in American Standard Test and Material document D-1004-94a was used to prepare test specimens. Immediately after removal from the cutting die, test specimens were measured at five points with an electronic caliper. Test specimens were placed into a specialized jig, and a Shimpo force gauge was used to measure tear strength. The tear test was performed no more than 10 minutes after mixing the alginate material with water. The tear strength was then calculated. One-way ANOVA was used to compare the mean force required to induce tearing for each of the four groups, followed by the Newman-Keuls pairwise multiple comparisons test. Results Results were considered statistically significant at p < .05. There was a statistically significant difference between alginate materials (p < .0001). The Newman-Keuls multiple comparisons procedure showed that Tare-Free Alg (514.5 g/cm) had a significantly higher tear strength value (p < .0001) than Jeltrate (259.0 g/cm), Identic (289.9 g/cm), and Kromopan (323.9 g/cm). Conclusions Tara-Free Alg had the highest tear strength value, followed by Jeltrate, Identic, and Kromopan.