Evaluation of Two-Body Wear of Different Resin Composite Restorations and the Effect of Layer Thickness

INTRODUCTION: This in-vitro study aims to comparatively assess the two-body wear of methacrylate/ormocer-based composites, methacrylate/ormocer-based bulk-fill composites(BFC), and nanohybrid CAD/CAM block restorations exposed to thermo-mechanical chewing simulation.METHODS: Mesial-occlusal-distal cavities were prepared in 100 noncarious extracted molars, and restored with Admira Fusion/A+Admira Fusion Flow/AF; Admira Fusion x-tra/AFX+Admira Fusion x-base/AFB; x-tra fil/X+x-tra base/XB; Tetric N-Ceram Bulk Fill/TB+Tetric N-Flow Bulk Fill/TFB; Tetric N-Ceram/T+Tetric N-Flow/TF; GrandioSo/G+GrandioSo Flow/GF; and Grandio Block/GB as per the manufacturer's instructions.The composites in bulk-fill groups were applied in 2-and 4-mm thick layers to investigate the effects of material thickness on wear.Restorations were exposed to 240,000 thermomechanical cycles in chewing simulator.Surfaces were scanned using laser scanner before and after loading.Volume loss was calculated using Geomagic Control program.The Kruskal-Wallis and Dunn tests were used for statistical analysis of the data.RESULTS: No significant difference was found between groups of the same materials layered with different thicknesses.A statistically significant difference in median wear values was observed between restorative material groups (p=0.006), and the wear values of A+AF(0.351) were higher than TB (4 mm)+TFB (2 mm)(0.045).CONCLUSION: CAD/CAM block and direct resin composite restorations did not differ in wear resistance.Also, all tested direct materials exhibited similar two-body wear resistance, except for ormocer-based composite, which had higher wear values.