中文摘要：

目的：评价复合树脂在垂直、肩台和斜面3种形态洞缘处的颜色偏移及匹配。方法：收集20颗颊面颜色为A2的离体前磨牙,在颊面中央制备长×宽×深为2 mm×2 mm×3 mm的窝洞,将龈方与牙合方洞缘分别备成肩台与斜面,其他洞缘保持垂直,用Clearfil AP-X（AP）和Clearfil Majesty（MJ）复合树脂各充填10颗牙,Crystal Eye比色仪测量洞缘处的色差,观察者主观评价充填体边缘颜色匹配性。用重复测量方差分析和卡方检验进行统计学分析。结果：两种树脂充填体由中心向洞缘,与牙面的色差都逐渐减小。比色仪测量与主观评价都显示AP树脂在3种洞缘的匹配性差异无统计学意义,MJ树脂在斜面洞缘的匹配性显著优于垂直洞缘。结论：复合树脂充填体在洞缘处会发生颜色偏移,光学性质中散射性强的复合树脂在颜色匹配上更易受到洞缘形态的影响,制备洞缘斜面可能会提高树脂颜色的匹配性。

英文摘要：

Objective： To evaluate effects of color matching of different cavosurface margins on the resin composites in vitro. Methods： Twenty extracted human premolars with an A2 shade buccal surface were used in this study. Rectangular shaped cavities（ 3. 0 mm depth,2. 0 mm width,2. 0 mm length）were prepared in the center of the buccal surfaces. The gingival and occlusal cavosurface margins were prepared to be either shoulder or bevel; the other cavosurface margins remained vertical. Ten teeth were filled with Clearfil AP-X（ AP）,the other ten with Clearfil Majesty（ MJ） and light cured. The color difference at the cavosurface margin area was measured using a spectrophotometer（ Crystal Eye） and evaluated by 3 observers subjectively. The data were statistically analyzed using repeated measures ANOVA and Chi-square test. Results： When measured by Crystal Eye,the color difference between the tooth and resin composite was reduced from the center of restoration to the cavosurface margin area. Both objective and subjective evaluations showed that for AP,the color difference at the cavosurface margin area had no statistical difference among 3 types of the margins; for MJ,the color difference at bevel margin area was significantly smaller than that at the vertical margin area. Conclusion： The resin composite restorations produced the color matching at marginal area. The color matching of resin composites with higher diffused light transmission property is more susceptible to the type of cavosurface margins.Preparing bevels may reduce the color difference between the restoration and tooth surface.