Effect of polishing-systems on surface-gloss of metal-free CAD/CAM restorative block

Objectives: The purpose of this study was to examine the effect of polishing-systems on the surface-gloss of various metal-free CAD/CAM restorative blocks.
Methods: Four polishing-systems; point type: Compomaster (CM, SHOFU), wheel type: Soflex Spiral (SP, 3M ESPE), disk type: Soflex XT (XT, 3M ESPE), brush type: Zircon Brite (ZB, DVA), were used. Three metal-free CAD/CAM restorative blocks; two hybrid-resin-composite blocks: Cerasmart (C, GC) and VITA ENAMIC (E, VITA), and one feldspathic-glass-ceramic block: VITABLOCS Mark II (M, VITA, as control) were selected. All restorative blocks were sectioned to discs of 3.0mm thickness each. The surface of every disc was prepared with a diamond bur to obtain the approximated surface-roughness of milled restorative by CEREC MC XL (SIRONA Dental Systems). Standardized-roughened surface of disc was polished with four polishing-systems according to the manufacturer’s instructions. The surface gloss of polished specimen was measured (n=4) by a glossmeter (IG-331, Horiba). The data were examined using two-way ANOVA and Tukey’s q-test.
Results: Mean surface-gloss values of four polishing-systems were ZB:52.4 > XT:43.2 ≧ SP:41.1 > CM:6.6. The values of three metal-free CAD/CAM restorative blocks were C:52.7 >E:30.9 > M:23.9. The surface-gloss was significantly influenced by the two factors, polishing-system and metal-free CAD/CAM restorative block, at p<0.01 respectively. The effect of polishing-system on the surface-gloss did vary with the CAD/CAM blocks. The gloss-value of ZB was statistically greater than the values of the other polishing-systems. The values of C and E were statistically bigger than that of M.
Conclusions: The effect of polishing-system on the surface-gloss did vary with the metal-free CAD/CAM restorative blocks examined. The performance of a brush type polishing-system, ZB, was statistically better than those of the other systems. The surface-gloss of two hybrid-resin-composite blocks, C and E, were significantly superior to that of a feldspathic-glass-ceramic block, M.