中文摘要：

目的：研究光固化模式对复合树脂聚合收缩率和表面硬度的影响,探讨这些因素的影响对临床工作的指导意义。方法：研究使用填料含量为76%（质量分数）的混合填料复合树脂,选择3种光固化模式固化树脂,分别为高光强模式、低光强模式和软启动模式,每种光固化模式分别固化树脂10 s和20 s。制备树脂聚合收缩样本和表面硬度样本,使用Acuvol聚合收缩仪测定树脂的聚合收缩率（n=7）,显微硬度仪测定树脂的表面硬度（n=5）。结果：高光强、低光强、软启动3种光固化模式固化树脂后聚合收缩率分别为2.95%±0.08%/3.06%±0.03%（10 s/20 s）、2.98%±0.12%/3.05%±0.13%（10 s/20 s）、3.03%±0.05%/3.11%±0.07%（10 s/20 s）,3者间差异无统计学意义（P〉0.05）;表面硬度分别为：（36.82±4.45）MPa/（47.58±3.16）MPa（10 s/20 s）、（32.30±1.33）MPa/（41.60±1.83）MPa（10 s/20 s）、（34.56±1.38）MPa/（44.62±2.13）MPa（10 s/20 s）,3者间差异有统计学意义（P〈0.05）,从高向低依次为：高光强模式〉软启动模式〉低光强模式。光固化输出能量与复合树脂固化后聚合收缩率呈低度正相关（r=-0.363,P=0.018）,其与复合树脂固化后表面硬度呈高度正相关（r=-0.890,P〈0.001）。结论：高光强模式有利于提高修复体的物理性能;应用软启动模式或低光强模式固化树脂时,应适当延长固化时间以增加光输出能量,使树脂固化后的物理性能不受影响。

英文摘要：

Objective： To investigate the effects of light-curing modes on the polymerization shrinkage and surface hardness of resins and to explore the related clinical relevance.Methods： Resins with filler content of 76%（mass fraction） were light-cured by high intensity,low intensity and soft start curing modes for 10 s and 20 s,respectively.Specimens for detecting volumetric shrinkage and surface hardness were prepared.Volumetric shrinkage was measured with Acuvol（n=7） and surface hardness were tested with an indenter（n=5）.Results： The volumetric shrinkage of composites cured by high intensity,low intensity and soft-start curing mode was： 2.95%±0.08%/3.06%±0.03%（10 s/20 s）,2.98%±0.12%/3.05%±0.13%（10 s/20 s）,and 3.03%±0.05%/3.11%±0.07%（10 s/20 s）,respectively.No significant difference existed among polymerization shrinkage of composites cured by the three light-curing modes（P0.05）.The hardness of composites cured by high intensity,low intensity and soft-start curing mode was：（36.82±4.45） MPa/（47.58±3.16） MPa（10 s/20 s）,（32.30±1.33） MPa/（41.60±1.83） MPa（10 s/20 s）,and（34.56±1.38） MPa/（44.62±2.13） MPa（10 s/20 s）,respectively.There existed significant difference among hardness of composites cured by the three light-curing modes（P0.05）.Polymerization shrinkage was correlated with energy density（r=-0.363,P=0.018）.Surface hardness was also correlated with energy density（r=-0.890,P0.001）.Conclusion： It would be better to use high intensity curing mode to improve the physical properties of restorations.In order to keep the physical properties of composites,it is necessary to prolong the curing time using soft-start/low intensity curing modes to increase the energy density.