Xue S H, Wang Y X, Xu T K, Jiang T
Beijing Da Xue Xue Bao Yi Xue Ban. 2020 Oct 18;52(5):943-947. doi: 10.19723/j.issn.1671-167X.2020.05.025.
To select the most effective method among different masking treatments, such as different thickness and transparence, tissue surface's opaque coating, and opaque resin cement to restore discolored teeth esthetically by porcelain veneer.
Four extracted intact maxillary central incisors were prepared for porcelain veneer restoration and each three heat pressed porcelain veneers from three thicknesses (0.8 mm, 1.0 mm, 1.2 mm) and two transparency(high transparence, HT and low transparence, LT))in Vita shade A2 were fabricated for each tooth, in total of 72 pieces. The surfaces of three prepared teeth were then painted to mimic situations of severe dental fluorosis, severe tetracycline teeth, and necrotic teeth. Each of the veneers was temporarily cemented to the corresponding tooth surface using try-in cements with three different colors (transparent, opaque, and yellow), then used the shade guide (3D master) and electronic colorimeter (easy shade) to record the shade of each porcelain veneer through hue, lightness, and chroma reading. After that, high-transparence porcelain veneers in thickness of 0.8 mm was fused with a layer of opaque porcelain in tissue surface, and were shade matched again after cementation. Statistic treatments were performed to analyze the difference in each masking method.
For each 0.2 mm increase in the veneer thickness of porcelain, the average lightness was reduced by 1 unit, while the chroma was not changed which was independent of the type of the resin cements. When the thickness of the porcelain veneer was decreased to 0.8 mm, the opacity effect was not remarkable even if a low-transparence porcelain veneer was used. Transparent and yellow resin cements had poor opaque performance, while opaque resin cement could reduce the lightness by 2 units and the chroma was also reduced. The opaque layer of the tissue surface could be applied uniformly, and the lightness and chroma could be reduced to Vita 2M1 to 2M1.5 levels regardless of the color of resin cements, which suggested a stable opacity effect for different discolored teeth in this study.
For porcelain veneer restoration of discolored teeth, thickened veneers are the most effective means to display a natural transmittance and color. Tissue surface's opacity coatings and opaque resin cements can also be used to reduce grayscale and increase lightness.
在不同的遮色处理方法中进行选择，如不同厚度和透明度、组织表面的不透明涂层以及不透明树脂粘结剂，以通过瓷贴面在美学上修复变色牙。
选取四颗完整拔除的上颌中切牙准备进行瓷贴面修复，每颗牙制作三种厚度（0.8mm、1.0mm、1.2mm）和两种透明度（高透明度，HT和低透明度，LT）的热压瓷贴面各三个，共72片。然后对三颗预备牙的表面进行处理，模拟重度氟斑牙、重度四环素牙和死髓牙的情况。将每种贴面分别用三种不同颜色（透明、不透明和黄色）的试戴粘结剂临时粘结到相应的牙面上，然后使用比色板（3D master）和电子比色仪（easy shade）通过色相、明度和彩度读数记录每个瓷贴面的颜色。之后，将0.8mm厚的高透明度瓷贴面在组织表面熔覆一层不透明瓷，粘结后再次进行比色。进行统计学处理以分析每种遮色方法的差异。
瓷贴面厚度每增加0.2mm，平均明度降低1个单位，而彩度不变，这与树脂粘结剂的类型无关。当瓷贴面厚度降至0.8mm时，即使使用低透明度瓷贴面，遮色效果也不显著。透明和黄色树脂粘结剂的遮色性能较差，而不透明树脂粘结剂可使明度降低2个单位，彩度也降低。组织表面的不透明层可均匀涂布，无论树脂粘结剂的颜色如何，明度和彩度均可降至Vita 2M1至2M1.5水平，这表明本研究中不同变色牙的遮色效果稳定。
对于变色牙的瓷贴面修复，增厚贴面是呈现自然透光率和颜色的最有效方法。组织表面的不透明涂层和不透明树脂粘结剂也可用于降低灰度和提高明度。
