IMMEDIATE SHADE VERIFICATION SYSTEM FOR CERAMIC RESTORATIONS

为单个前牙陶瓷实现精确的颜色匹配

To achieve an exact color match for a single anterior ceramic restoration is one of the most challenging tasks in fixed prosthodontics. Many methods have been described in the literature to facilitate this process. The most promising solution utilizes an organic liquid binder with a specific index of refraction(1.49 to 1.51) which matches that of dental porcelain. When mixed with un-dyed pre-sintered dental porcelain, the binder allows immediate, direct visualization of the post-sintered porcelain color. More than a custom shade-tab, this technique provides the laboratory ceramist with precise information on the color, location, and thickness of all the porcelain layers that produced the verifies, desirable esthetic effects. A drawback is that the organic liquid binder-porcelain powder mixture remains in a liquid state, which makes transport difficult. In our approach, a mixture of visible light-cured(VLC) polymers with the proper refractive index is being considered as possible replacement or addition to the organic binder. Earlier results, using only polymers such as bisphenol-glycidyl methacrylate, urethane dimethacrylate, and triethylene glycol- demethacrylate, demonstrated that the molar volume of porcelain powder in the polymer-ceramic mixture is critical. A 5% variation can result in significant optical differences. This renders the technique unpractical because one would need to make precise measurements for each of the dental porcelain systems. Some porcelain systems, such as the Vita Omega, have over 70 powders. Furthermore, the required molar volume often produced excessively viscous mixtures with poor handling characteristics. My recent work suggests that powder molar volume is less critical when a VLC polymer-organic binder mixture is used. However, color stability is questionable due to possible chemical degradation of the polymers by the organic components. Chemically compatible polymer- organic liquid combinations are being considered for the proper optical properties. Shade tabs of post-sintered ceramics have been fabricated for comparison with the polymer-organic liquid-powder mixtures. Keywords: refractive index, dental porcelains, polymers, color