The effect of coloring liquids on color of zirconia frameworks and bond strength zirconia-veneer ceramic

Despite its popularity, there are limitted studies in literature regarding effect of coloring procedures on physical properties of zirconia. The aims of the study are to evaluate and compare the color of liquid shaded and pre-colored zirconia and to investigate the effect of coloring liquids on the bond strength between veneer ceramic and zirconia core. Sixty-four cube-shaped specimens were fabricated using uncolored zirconia blocks by CAD/CAM and divided into four groups randomly (n=16). G30, G60 and G120 groups were subjected to coloring liquids for 30 sec., 60 sec. and 120 sec. respectively. Control bond strength group (CBS) was subjected to no coloring procedure. After coloring, color differences between test groups and precolored zirconia group (PCZ) (n=16) were evaluated by using a spectrophotometer. Prior to shear-bond test, veneer ceramic was applied on zirconia and sintered. Shear bond test was conducted with Testometric with a cross-head speed of 1 mm/sec. The statistical data were analysed with one-way ANOVA and Tukey HSD test (p≤0.05). Weibull analysis was performed and Weibull modulus was calculated for each group. PCZ group (E=77,34) was statistically different from all groups. G60 was statistically different from G30 and G120. PCZ has the highest bond strength value (31,5 MPa) and was statistically different from G120 and CBS. The CBS had the lowest bond strength value (19,1 MPa) and was statistically different from G60. The Weibull modulus was calculated as 64,78 for PCZ and 0,1 for G120. Within the limitations of this study, it was shown that coloring liquids had unpredictable outcomes regarding the color and bond strength. This procedure should be standardised. Anahtar Kelimeler: Zirkonya, renklendirme solüsyonları, bağlanma dayanımı