Effect of Filler Particle Size on Wear Resistance of Resin Cement

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The purpose of this study was to evaluate the effect of filler particle size on wear resistance of resin cement. Materials tested in this study were four experimental dual-cure (DC) resin cements (Kuraray Co., Japan), which contained fillers of different sizes. The cusps of the extracted human molars were ground to a flat occlusal surface using a 600 grit silicon carbide paper. A rectangular cavity was prepared in the occlusal surface of each tooth. Ceramic inlays were then fabricated using the CEREC 2 system. The inlays were cemented with the respective experimental resin cements and adhesive systems according to manufacturer's directions, The restored surface was finished and polished by wet-grinding with 800 grit silicon carbide paper. Six specimens were prepared for each resin cement. Half of the specimens were subjected to three-body wear test for 200,000 cycles, and the others were subjected to toothbrush abrasion for 30,000 cycles, both using an in vitro wear testing device. The … More worn surface of the resin cement was scanned and traced, using a profilometer (Surfcom 475 A, Tokyo Seimitsu) at 8 different points. Replicas were made and observed under SEM.The vertical gap depth of each resin cement was measured on the respective profilometric tracing as the wear value. The data was statistically analyzed by one-way ANOVA.The results are as follow :There were significant differences among the wear values of the resin cements for both wear test, except for those of resin cement I and resin cement IV.The results of the toothbrush abrasion test showed that resin cement with large filler exhibited the least wear. On the other hand, the three-body wear test showed a different result. The resin cement with large filler exhibited the most wear. SEM observation showed filler particles protruding from the worn surface of resin cements IT and III after toothbrush abrasion testing and small defects caused by the exfoliation of particles after three-body wear testing. The worn surfaces of resin cement I and IV with filler particle size of less than 1.0 mum were seem to be smoother than those of the other cements. Less