Comparison of translucency properties of different zirkonia all ceramic systems

. Partially stabilized zirconia with yttrium (Y-TZP) has become the preferred core material in all ceramic restorations with superior mechanical properties. Due to its polycrystalline composition, it is more opaque that is limited its optical properties. For this reason, Y-TZP core materials have to be veneered for increasing their colour and translucency properties to obtain more estetic restorations. To increase estetic properties of zirconia ceramics and to eliminate the veneering failure could be a fabrication of monolithic zirconia which consists of a single zirconia material without any veneering. The monolithic zirconia material is to be an alternative to core-veneer system with their high translucency properties. The purpose of this study is to compare translucency properties of the different core- veneer ceramic systems to different monolithic systems these are made of A2 colour. In the study, optical properties of 2 different Y-TZP systems compare with the 2 different monolithic sytems these are made by same manufacturers of Y-TZP systems. 10 disc- shaped specimens its thichness are 0.5 mm preperad for each Ceramill and Lava systems (n=10). On the core specimens are added IPS e.max Ceram veneer ceramic which is suitable to zirconia systems and finished final thickness is 1.5 mm. 10 disc shaped specimens its thickness are 1.5 mm preperad or each monolithic zirconia groups which are Ceramill Zolid and Lava Plus High Translusens zirconia (n=10) and finished in A2 colour by using colouring liquid which is advanced by systems. There transluceny measurements are made with the spectrophotometer CM- 2500d/2600d to use the contrast ratio method. First measurement was made between Ceramill and Lava core samples. Second was made after veneer ceramic materials added on the core specimens between Ceramill and Lava and also monolithic zirconia groups before glaze procedure. Third measurement was made between all groups after glaze procedure. In the end of the study, parameters were evaluated with the Kolmogorov-smirnov test and detected they are not suitable for normal distribution. When the datas of the study are evaluated, comparison of the parameters between four groups were performed Kruskal Wallis test. Comparison of two groups were performed Mann Whitney U test. And comparison of the parameters in groups were performed Friedman and Wilcoxon Sign tests. Significance p <0.05 level were evaluated. Results of the study, measurements of the Ceramill and Lava core samples showed values of contrast ratio of Ceramill groups are less than the values of Lava groups. So, Ceramill core specimens are found more translucent than Lava core samples at the thickness 0.5 mm. After adding veneer ceramic, the contrast ratio values of Ceramill and Lava groups were closed to each other with decreasing. Between the classical zirconia groups are Ceramill and Lava samples and the monolithic zirconia groups are Ceramill Zolid and Lava Plus High Translusens zirconia samples were found no significant differences in the contrast ratio values before and after the glaze procedure at the thickness 1.5 mm. At all the groups after the glaze procedure the contrast ratio values decreased significantly.