Comparative Study On Translucency Of Dental Zirconia Materials

Objectives:To measure the translucency of 11 brands of dental zirconia material and one lithium disilicate glass ceramic,provide a selection basis for clinical all-ceramic restoration,and compare the differences in micro structure and composition between domestic and imported dental zirconia materials.Methods:Comparisons were made between the translucency of 11 brands of dental zirconia materials(from Upcera,Aidite,Vitang,XTcera,Zotion,Besmile,Besmile Bojingci,VITA,Noritake,Zirkonzahn and Wieland Dental)and one lithium disilicate glass-ceramic(IPS e.max Press from Ivoclar Vivadent).These 12 brands were divided into groups A?L(n=5).The colorless zirconia specimens and A1 IPS e.max Press specimen were cut to a size of 10×10×0.5±0.05 mm,and direct measurement was performed with a spectrophotometer(Lambda 750S).The transmittance percentage(T%)of the specimens in a visible light wavelength range of 380?780 nanometers was measured 3 times for each specimen.Indirect measurement was performed with a VITA Easyshade Advance 4.0.The CIE L*a*b*values of the specimens were measured on black and white background tiles,and each specimen was measured 3 times to obtain their average values.The translucency parameters(TP)of the specimens were calculated according to the formula TP=[(L B-L w)2+(a*B-a*W)2+(b*B-b*w)2]1/2.The measured data was analyzed via one-way ANOVA and LSD testing using SPSS 19.0 software(p<0.05).One specimen was then selected from each group to undergo scanning electron microscopy(SEM)and chemical composition analysis.Results:1.The results of direct measurement were statistically significant(p<0.05).The translucency of the IPS e.max Press sample was found to be significantly higher than that of the zirconia samples.The translucency of Vitang was higher than that of Upcera,Aidite,Zotion,Noritake and Wieland Dental;the translucency of XTcera was higher than that of Wieland Dental;the translucency of VITA was higher than that of Upcera,Aidite,XTcera,Zotion,Besmile,Noritake,Zirkonzahn and Wieland Dental;the translucency of Besmile Bojingci was higher than that of Upcera,Noritake and Wieland Dental:and the translucency of Zirkonzahn was higher than that of Noritake and Wieland Dental.2.The results of indirect measurement were statistically significant(p<0.05).The results showed different levels of translucency in the following order:IPS e.max Press>Zirkonzahn>Vitang,Zotion and VITA>Besmile Bojingci and Wieland Dental>Upcera and Besmile>Aidite,XTcera and Noritake.3.The SEM images of the 11 groups of zirconia specimens showed compactly arranged grain,non-grown grain,micropores and other microstructures.The microstructures of each group were different.Irregularly arranged lamellar lithium disilicate crystals and micropores could be observed on the surface of the IPS e.max Press.4.The chemical composition analysis showed that the 11 groups of specimens included ZrO2,Y2O3,Al2O3 and HfO2.The composition and content of the specimens tested in this experiment were in line with the quality standard "Guiding Principles for the Registration of Zirconia Ceramics Products for All-Ceramic Crowns".The IPS e.max Press was found to mainly contain Li2Si2O5,K2O,P2O5,ZnO,MgO,Al2O3,Na and W elements.Conclusions:1.Combining the two measurements,the translucency of Ivoclar Vivadent's IPS e.max Press was found to be higher than that of the 11 zirconia brands.2.According to the color of the abutment and the measurement data of this experiment,dental zirconia materials with different levels of translucency can be selected for the aesthetic restoration of the anterior region,zirconia core of the posterior region and zirconia all-ceramic crown restoration when the interalveolar space is insufficient.3.Compared with imported European zirconia,the microstructures of domestic zirconia still have certain shortcomings in terms of micropores,grain size and uniformity of grain growth.Domestic specialists require further research methods to improve the microstructural characteristics of zirconia and increase its translucency.4.The composition of the domestic zirconia tested in this experiment was in line with the quality standard,and showed no significant differences from the composition of the imported zirconia.In terms of material composition,the quality of domestically produced materials is close to the international level.