热循环对二种粘接剂的树脂-牙本质界面粘接强度的影响

目的:评价在离体条件下热循环对树脂-牙本质界面粘接强度的影响。方法：选取60颗人无龋磨牙，在低速锯下去除冠部牙釉质，暴露出牙本质，用300目、600目的碳化硅砂纸依次抛光处理后，按热循环处理方法随机分成3组，各组内用全酸蚀粘接剂系统中的Single Bond和自酸蚀粘接剂系统中的Adper Prompt分别粘接处理10颗牙。第1组（n=20），无热循环处理,试件在37℃的蒸馏水中保存24 h后取出进行剪切强度(shear bond strength)测试;第2组(n=20)，试件热循环处理500次;第3组（n=20）,试件热循环处理1 000次。后两组的温度均设定为5℃~55℃，闭模时间为30 s，传递时间20 s。热循环机处理后的试件在37℃蒸馏水中保存24 h后取出进行剪切强度测试。3组均在Instron1121万能材料试验机上进行剪切强度测试，加载的速度为1 mm·min^-1。剪切强度测试结束后，每组选取Single Bond和Adper Prompt试件的断裂面各1例，进行扫描电子显微镜的观察。结果：热循环0、500及1 000次后的剪切强度（MPa）依次为(Single Bond)18.12±3.36、17.62±3.61及16.93±2.66;(Adper Prompt)13.22±2.76、12.93±2.93及11.17±2.63。不同的热循环处理组间的剪切强度差异均无显著性（P>0.05）;各组中Single Bond的剪切强度显著高于Adper Prompt(P<0.05)；扫描电子显微镜显示,Single Bond试件断裂面内的树脂突多于Adper Prompt。结论:短期内，热循环对树脂-牙本质界面的剪切强度没有显著的影响；在本研究中所选用的全酸蚀粘接剂系统的粘接强度显著高于自酸蚀粘接剂系统的粘接强度。

Effect of thermal cycling on resin-dentin interface of two bonding agents

Objective To evaluate dentin-resin interface on bond strengths under different thermal cycling treatments in vitro.Methods Sixty intact non-carious human molars were selected,the occlusal enamel were removed using a low-speed-saw to expose a dentin surface,dentin surface were polished with 300 grit,600 grit silicon carbide paper successively.Sixty specimens were divided randomly into three groups according to different thermal cycling treatments,in each group,two bonding agents were used: Single Bond,a total etch bonding system;and Adper Prompt,a self etch bonding system,with ten teeth in each agent.In group Ⅰ(n=20),there was no thermal cycling treatment,after preserved in 37℃ water for 24 h,shear bond tests were performed.Another forty specimens were assigned as group Ⅱ(n=20) and group Ⅲ(n=20).Specimens were submitted to thermal cycling,(500 cycles) in group Ⅱ and 1 000 cycles in group Ⅲ.The treatment temperature in groups Ⅱand Ⅲ was 5℃-55℃.The dwell time was 30s in each bath with a transfer time of 20 s.After 24 h storage in distilled water at 37℃,shear bond strength tests were performed.Shear bond strength tests of all groups were conducted in a instron 1121 universal testing machine at a cross-head speed of 1 mm·min~(-1).After shear bond strength test,one of Single Bond fractured specimens and one of Adper Prompt fractured specimen were selected in each group to be examined under SEM.Results Shear bond strengths(MPa)after 0,500 and 1 000 thermal cycles were: Single Bond(18.12±)3.36,17.62±3.61 and 16.93±2.66;Adper Prompt:13.22±2.76,12.90±2.93 and 11.17±2.63.There were no significant differences of shear bond strengths among different thermal cycling treatment groups((P>0.05);) Single Bond provided significantly higher shear bond strengths than Adper Prompt in all groups((P<0.05).) All fractures of interfaces showed resin tag create with Single Bond more than with Adper Prompt.Conclusion In short terms,thermal cycling dosen′t influence significantly the shear bond strength of the resin-dentin interface.Compared two dentin-bonding systems used in this study,total etch bond system provide significantly higher strength than self etch bond system.