In Vitro Study of Wear, Fatigue, and Colour Behaviour of Novel CAD/CAM Monolithic All-Ceramic Materials

Abstract

<strong>Objectives.</strong> To measure the wear resistance and abrasiveness of CAD/CAM ceramics, including partially crystallized lithium disilicate (PLD), experimental fully crystallized lithium disilicate (FLD), zirconia reinforced lithium silicate (ZLS), super-translucent monolithic zirconia (SMZ) and ultra-translucent monolithic zirconia (UMZ). <br /> <strong>Methods.</strong> Blocks were sectioned into 12 mm × 6.5 mm × 1.5 mm rectangular shaped specimen. Surfaces were mechanically flattened and polished using silicon carbide papers. PLD specimens were subjected to a combined crystallization/glazing firing cycle. Ceramic specimens were mounted to the wear device and tested for 200.000 cycles against human premolars at 25 N force and 2mm sliding distance. Artificial saliva was used as a lubricant. The teeth were scanned using micro-CT before and after the wear test and the generated models were overlapped to determine the volumetric tooth loss. Weights and surface roughness (Ra) values of specimens were measured before and after the test and the differences were calculated and recorded. SEM and EDX were used for microstructural and chemical analysis. Statistical analysis was performed using one-way Anova or an equivalent test for non-parametric results. The significance level was set at P=0.05. <br /> <strong>Results.</strong> The ceramic and antagonist wear rates were affected by the material (p<0.001). PLD and ZLS showed the highest ceramic and antagonist wear, whereas UMZ and SMZ showed the lowest wear values. Experimental FLD group showed comparable antagonist wear values and significantly less ceramic wear compared to PLD and ZLS.