| With excellent machinability, good translucency and proper strength, mica glass-ceramic has become one of ideal dental ceramic materials that can be fabricated with CAD/CAM. However, the lack of intrinsical coloration restricted its widespread application in dental clinic. In this study, the inner-colorized mica glass ceramic blocks were fabricated by appending the pigments to a novel mica-glass-ceramic based on SiO2-Al2O3-Mg-Na2O-K2O-F mica glass-ceramic system for dental application by two ways. One is melting and casting technology, another is sintering technology. The results are as follow:1.The objective of this study was to observe color parameters of IPS e.max all-ceramic systems and give reference for coloration of one kind of mica glass-ceramic. The results showed the chroma values of IPS e.max blocks were L: 68.4893.26, a:-0.092.80, b:-3.2613.49. The relative translucency of the blocks were between 0.6430.927.2.The objective of this study was to evaluate the coloration effects of three kinds of pigments with different concentrations on the mica glass-ceramic by melting and casting technique. Different concentrations of three kinds of pigments were added into samples, the chroma values were measured with chroma meter. The colors achieved by the different pigments were presented in the CIELab system. When adding CeO2, the samples turned yellow and the b value increased, but L value decreased as the amount of CeO2 increased.When adding Er<sub>2O3, the samples turned pink and the a﹡value increased as the amount of Er<sub>2O3. When adding Fe<sub>2O3, the samples turned from yellow to brown, and a﹡ value increased, L value decreased as the amount of Fe<sub>2O3 increased, while the b value firstly increased and then decreased.3.The objective of this study was to investigate the effects of different heat treatment process on the coloration of mica glass-ceramic. Nine kinds of heat treatment process including different temperature and holding times were chosen to treat the glass containing 1% CeO2. The chroma value and relative translucency of samples were measured with chroma meter. The microstructure of samples were observed with SEM and analyzed with XRD. The results showed the mica glass-ceramic turned different shade and translucency with different heat treatment process for same kind of sample. The SEM and XRD results suggested these differences are related with the different structure. The preferred heat treatment process was treated at 660℃for 1h.4.To evaluate the effects of CeO2 on the microstructure and property of SiO2-Al<sub>2O3-Mg-Na2O-K2O-F system, 2-5%CeO2 was added to base glass system respectively. DTA, XRD and SEM were used to observe the crystallization behavior, crystalline phases and microstructures of the samples. Three point bend strength, micro hardness and machinability were also measured. When adding CeO2 to the glass-ceramics, the main crystalline phases were not changed, but the crystal became larger. With increasing of the CeO2 concentration, three point bending strength firstly increased and then decreased, machinability increased and micro hard ness firstly decreased and then increased. The results suggested that the addition of CeO2 changed the crystalline structure, increased the grain size of mica and machinability of mica glass-ceramics. Appropriate addition of CeO2 does not change the strength of glass-ceramics. 5.To match the some special color porcelain corresponding to Vita shade, different concentrations of three kinds of pigments were added to the basic glass, and then the samples were treated with different heat-treatment process. Chroma value and translucency analysis were performed. Sample with special color were produced. The color difference analysis showed that the color of the materials obtained in this study was similar to that of Vita A1 and A2 shade.6.To fabricate the mica glass-ceramic by sintering technology, the effects of different sintering temperatures on crystalline structures and shrinkage rate were investigated. The relationship between shrinkage rate and sintering temperature showed that the increase of sintering temperature from 600℃to 850℃leads to the increase of the shrinkage rate. The XRD showed the crystalline phase was fluophlogopite mica when treated at 850℃.Improving crystallization temperature increased the rate of crystal and aspect ratio of the mica. The glass sintered at 850℃has good sinterability.7.To investigate if the relationship of different concentration of pigments and their reflective spectrums is fit to the computer color matching theory, the monochromatic samples with different concentrations of zirconate-based pigments were prepared by sintering technology. Their chroma values and reflective spectrums were measured and investigated. The result indicated that the relationship between the concentrations of pigments and the chroma values accorded with the principles of pigmentation color characteristic, and the spectral reflectivity of monochromatic samples were feasible for establishing database of computer-color-matching software. |
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