Effect of different sintering situations on optical characteristics of monolithic zirconia

Different sintering temperatures can affect the optical, mechanical and structural properties of the monolithic zirconia material. However, there is no consensus on the ideal sintering condition for this material. The aim of this study is to examine the effect of different sintering temperatures on the particle size, translucency parameter (TP00), and color change after aging (∆E00) according to CIEDE2000 of monolithic zirconia materials with various colors. A total of 123 samples in A3, B3, C3, D3 colors were prepared from monolithic zirconia material (inCoris TZI C, Sirona Dental; Germany) to be sintered at three different temperatures (1450 ° C, 1510 ° C, 1600 ° C). After sintering, L *, a *, b *, C (chroma) and h (hue) values of the samples were measured with a spectrophotometer (Easy Shade Advance 4.0 Vita Zahnfabric; Germany) on a white and black background and TP00 values (n = 10) were calculated. Subsequently, the samples were aged in autoclave for 2 hours, and the E00 values were calculated by repeating the color measurements on the white background. Scanning electron microscopy (SEM) images were used for particle size analysis. Data were evaluated using 2-way analysis of variance (ANOVA) and Tukey HSD test (P≤0.05). The highest TP00 value was recorded in A3 color for samples sintered at 1450 ° C and 1510 ° C, and B3 at 1600 ° C. The lowest TP00 value for all temperatures was recorded for the C3 color. It was observed that TP00 values increased in all color groups with the increase of sintering temperature. There was no significant difference in ∆E00 values between color groups at all sintering degrees (P> 0.05). While a significant increase was observed in particle size with increasing temperature (P≤0.05), no significant difference was observed in the evaluation before and after aging (P> 0.05). Translucency values of all color groups increased with increasing sintering temperature. However, different TP00 values were observed in samples with different hue values sintered at the same temperature. It was determined that ∆E00 values formed by aging give results below the perceptibility level of the human eye for all sintering temperatures.