Title: Comparison of different methods for measuring flow properties of impression materials
The aim of this study is to compare different methods for measuring flow properties of impression materials. The flow properties were measured by shark-fin test and consistency test. Twelveaddition silicone impression materials(four commercial productseach with heavy, medium, and lightbody material) and two agar impression materials were usedin two different methods (n=10 per material and method). Shark-fin test was performed using a sharkfintestingapparatus(3M ESPE, Seefeld, Germany). A weighted metal castwas suspended above a cup of impression material. The castwas dropped into the impression material, which displaced the material and caused it to flow into a triangular notch within the cast, creating a “shark fin.” Consistency testwas determined according to ISO 4823(2015). The data were statistically analyzed by correlation analysis and two-way ANOVA with Tukey test (p=0.05) using PASW 18.0 (SPSS Inc., Chicago, U.S.A.). Good correlation was found between the shark-fin test and the consistency test (R2 = 0.587, p = 0.000). Strong correlation was found between the methods in addition silicone impression materials (R2 = 0.915, p = 0.000), however, correlation was not found in agar impression materials (R2 = - 0.249, p = 0.145). In detail, good and strong correlations were found in addition silicon materials with each consistency type (heavy body: R2 = 0.368, p = 0.019, medium body: R2 = 0.755, p = 0.000, light body: R2 = 0.865, p = 0.000) and mild correlation was found in three commercial addition silicone products. There were significant differences among the impression materials and test methods. Based on the results of this study, shark-fin test could be substituted for consistency test in measuring flow properties of addition silicone impression materials or one of the optionsfor them.