| By combining the dental CAD/CAM technology with elements of glass infiltration technology, a new way to fabricate all ceramic restorations was developed. In previous research, the technology of producing partially sintered porous alumina block had been solved. This study attempts to make a solution on how to match the color between glass infiltrating alumina core ceramic and the Vitadur Alpha veneering ceramic. The effects on the color of infiltrating alumina ceramic of different metal oxides were investigated. Based on these study, it was found that lightness of the core material is the most important factor, followed was chroma, and the least is hue. Then, four kinds of infiltration glass powder with specified color were developed successfully. The color and its stability of infiltration alumina ceramic were tested. The color match between alumina core ceramic and the Vitadur Alpha veneering ceramic were also tested. The physical, mechanical and biocompatibility properties of infiltration glass and alumina core ceramic were investigated. Some progress in theory and practice of dental ceramic color match has been achieved. The results indicated:1. Cerium oxide could effectively enhance b value of the alumina core materials, but its ability of reducing L value and enhancing a value was a little. Combined use of cerium oxide and erbium oxide could shift the color from yellow-green to yellow-red, while it's ability of reducing L value was still weak;when the ratio of the two oxides was fixed by weight, the color parameter changes linearly with the ratio;when the overall mass by weight was fixed, the color shift corresponds to the change of mol of individual oxide. When ferric oxide was added, L value was decreased and the color was shifted to more yellow-red direction.2. After infiltration with Vita In-Ceram glass powder, regarded lmm thickness as the standard, the color parameters of alumina core ceramic were L: 69.39-78.41, a: 1.82-4.02, b: 18.35-24.42;when infiltration with AG1 - AG 4glass powder, the color parameters of alumina core ceramic were L:68.80~78.44, a: 1.32—4.75, b: 16.86-21.86. The color distribution of two groups were similar with Vita In-Ceram laboratory shade guide. The differences between the two groups of glass powder were: b value and chroma of the AG 3 core ceramic were lower than that of AL3 core ceramic, while a value was higher;b value and chroma of the AG 1 and AG 2 core ceramic were lower than that of AL1 and AL2 core ceramic. The reflectance curve of core ceramic infiltrated by AG 1 ~ AG 4 glass powder demonstrated the similar trend as that of the core ceramic infiltrated by Vita In-Ceram glass powder.With the increased infiltration time and elevated infiltration temperature, L value decreased, while a value and b value increased, but the color difference was still within the clinical acceptable range. All of the 4 color serials infiltrated core ceramic were veneered with Vitadur Alpha veneering ceramic, the color differences could be accepted clinically after veneered with 0.3mm opaque dentine and 0.4mm dentine ceramic.3. Density, thermal expansion coefficient, Vicker's hardness, three-point bending strength and fracture toughness of infiltration glass were 2.21g/cm3, 6.41x10-6 °C -1 , 6.39±0.12GPa, 112.08±10.58MPa , 2.01±0.09MPaml/2 respectively.4. Density, thermal expansion coefficient, Vicker's hardness, three-point bending strength and fracture toughness of infiltration glass ceramic were 3.88g/cm3, 7.68x10-6 °C -1 , 9.89±0.18GPa, 386.99±27.72MPa , 3.70±0.13MPaml/2 respectively.5. Before the clinical application, a series of experiments should be done to determine the biocompatibility of the infiltration alumina ceramic. The results showed that the infiltration alumina ceramic had good biocompatibility and was suitable for clinical restoration.It could be concluded that excellent color compatibility exists between alumina core ceramic infiltrated by AG1 ~ AG4 glass powder and the Vitadur Alpha veneering ceramic. It got great progress in theory and practice on dental ceramic color match.
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