A comparison of the wear resistance and hardness of indirect composite resins

Statement of problem. Various new, second-generation indirect composites ha ve been developed with claimed advantages over existing tooth-colored resto rative materials. To date, little independent research has been published o n these materials, and the properties specified in the advertising material s are largely derived from in-house or contracted testing. Purpose. Four second-generation indirect composites (Artglass, belleGlass, Sculpture, and Targis) were tested for wear resistance and hardness against 2 control materials with well-documented clinical application. Human ename l was also tested for comparison. Material and methods. Twelve specimens of each material were fabricated acc ording to the manufacturers' directions and subjected to accelerated near i n a 3-body abrasion, toothbrushing apparatus, Vickers hardness was measured for each of the tested materials, and energy dispersive x-ray (EDX) spectr oscopy was performed to determine the elemental composition of the composit e fillers. The statistical tests used for wear and hardness were the Kruska l-Wallis 1-way ANOVA test with Mann-Whitney tests and 1-way ANOVA with mult iple comparisons (Tukey, HSD). The Pearson correlation coefficient was used to determine the existence of a relationship between the hardness of the m aterials and the degree to which they had worn. The level of statistical si gnificance chosen was alpha=.05. Results. The control material Concept was superior to the other composites in wear resistance and hardness and had the lowest surface roughness. Signi ficant relationships were observed between depth of wear and hardness and b etween depth of wear and average surface roughness. Enamel specimens were h arder and more wear resistant than any of the composites. EDS spectroscopy revealed that the elemental composition of the fillers of the 4 new composi tes was almost identical, as ws the composition of the 2 control composites . Conclusion. The differences in wear, hardness, and average surface roughnes s may have been due to differences in the chemistry or method of polymeriza tion of the composites. Further research in this area should be encouraged. It was also apparent that the filler present in the tested composites did not exactly tit the manufacturers' descriptions.