Evaluation of the optical properties of zirconia reinforced lithium silicate blocks – in vitro study

Materials and method: IPS e.max CAD, Celtra-Duo and Vita-Suprinity CADCAM blocks were used in this study. Total of 144 specimens (0.7x12x14) were prepared, glazed and cemented on white acetal resin (DelrinÒ, DuPont, USA) with translucent dualcure resin cement (NX3 Third Generation, Kerrdental, USA). Thermocycling was performed at 5000 cycles (50C-550C) and each group was randomly separated into 4 subgroups (n=12): distilled water, coffee, tea and wine and steeped in solutions for 180 hours (10 years' clinical simulation). Color change was measured with spectrophotometer (Vita-Easyshade V, Vita-Zahnfabrik, Germany) and gloss values were measured with glossmeter (SGM60, PCE Instruments, Germany). Color change (DE) was calculated using CIEDE2000 formula. Gloss change (DGU) was calculated using [GU1-GU2] formula. Gloss, L*, a*, b* and DE were analyzed by two-way variance analysis. In cases where the main effects are significant, multiple comparisons with Bonferroni correction are performed (p=0.05).