AIM: To study the effect of dry and wet environment on the polymerization shrinkage of threerndental resin composites . MEHTODS: 18 freshly extracted human mandibular third molars were collected, MO cavities with the width of 1/3 of buccolingual cusp distance and depth of 2 mm were prepared on the molars. Cavities were treated with G-BOND bonding system except for P90 with its own bonding system, then three commercially available dental resin composites GRADIA DIRECT-P, Z350 and P90 were used to fill the cavities respectively( n =6). The teeth were then divided into wet and dry groups randomly (n = 3). The shrinkages of the composites and the deformation of the teeth were measured by electronic speckle pattern interferometry (ESPI) immediately after light cure for 40 s under the 650mW/cm2. RESULTS: Among the three dental resin composites, GRADIA DIRECT-P showed the largest polymerization shrinkage and tooth deformation, while P90 showed the minimum. The polymerization shrinkage in the moist environment was less than that under dry condition. CONCLUSION: The environment has a certain impact on the polymerization shrinkage of the dental resin composite. In wet environment, the polymerization shrinkage is less.%目的:测试干燥、湿润环境对3种光固化复合树脂聚合收缩的影响.方法:取18个新鲜拔除的下颌第三磨牙,制备近中邻(牙合)(MO)洞,洞宽为颊舌牙尖距的1/3,洞深为2 mm,然后分别用GRADIA DIRECT-P、Z350和P90树脂充填窝洞(P90用其自带粘结剂,其余均用G-BOND粘结剂处理洞壁)(n=6),并随机分成干燥组和湿润组(n=3).在650 mW/cm2光源下,光照固化40 s后采用电子散斑干涉技术测量树脂修复体的(牙合)面、近中邻面收缩和牙齿颊面的变形情况.结果:3种树脂中GRADIA DIRECT-P的收缩量和牙齿变形量最大,P90的收缩量和牙齿变形量最小；湿润环境可降低树脂修复体聚合收缩量和牙齿的变形量.结论:环境对光固化树脂的聚合收缩有一定影响,湿润环境下,其聚合收缩明显减小.
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