Comparison of In-Vitro Wear with Physical Properties of Composite Resins

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Objective: This study compares in-vitro soft, third-body wear with physical properties of composite resins.   Method: The development of a soft, three-body in-vitro wear method was previously described (IADR Abst. #  424, March 2007).  In this study,  physical properties of composite resins including compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), and hardness (H) were measured and compared to the wear data.  Properties were measured according to ISO 4049 (FS), ADA Specification No. 1 (CS), No. 27 (DTS) and Rockwell 15T instructions.   Five samples each were measured and the means and standard deviations (S.D.) calculated.  All samples were cured according to manufacturers instructions and stored in 37șC water for 1 week before testing.   Anova analysis (p<0.05) was conducted for each property to determine significant differences between the means.  The physical property data were plotted against soft-third body wear and correlation coefficients were reported for positive correlations.  Results: The individual data for several products are reported in the attached table.  Superscript letters in each row indicate significant differences between the means.  Positive correlations were found for plots of CS (0.73) and H (0.82) vs. wear; whereas poor correlation was found for DTS and FS.  Threshold limits for CS (379 MPa) and H (84) were found, corresponding to the y-intercept of a linear trendline.  Conclusion:  Positive correlations were found for CS and H vs. soft, three-body wear.  The plots indicate that threshold limits may exist for CS and H where wear approaches zero (research funded by Kerr Corp.).