缩短酸蚀时间对龋影响乳牙牙本质粘结强度的影响

Effect of shortening the etching time on bond strength to caries-affected dentin of deciduous teeth

目的探讨不同酸蚀粘结系统下缩短酸蚀时间对龋影响乳牙牙本质粘结强度的影响。方法选取因滞留拔除乳前牙42颗,制备龋影响乳牙牙本质平面。随机分为6组(n=7),分别采用三种酸蚀粘结系统;每种系统下酸蚀时间分别为说明书规定时间和缩短一半的时间。制作树脂粘结试件,电子万能试验机测定剪切粘结强度(shear bond strength,SBS)值,扫描电镜观察断裂面形态。结果全酸蚀系统和一步法自酸蚀系统下缩短酸蚀时间并不影响SBS值(P>0.05);两步法自酸蚀系统下,正常时间组SBS值高于缩短时间组(P<0.05)。六组间比较,两步法自酸蚀系统正常时间SBS值最高。扫描电镜观察结果显示各组测试后断裂面主要发生在混合层,全酸蚀系统下,断裂面多在混合层中上部;一步法自酸蚀系统下断裂面牙本质小管大部分呈空虚状态;两步法自酸蚀系统下断裂面中树脂与胶原纤维结合紧密。结论全酸蚀系统和一步法自酸蚀系统下,可缩短酸蚀时间。两步法自酸蚀系统下采用正常酸蚀时间粘结效果更好。

Objective To evaluate the effect of shortening the etching time on bond strength of different adhesive systems to caries-affected dentin （CAD） of deciduous teeth. Methods Flat dentin surfaces from 42 stranded deciduous anterior teeth were induced to caries-affected dentin of deciduous teeth. The specimens were assigned to 6 groups according to bonding approach and etching time randomly （each n = 7 ）. Three different adhesive systems were used and in every system half of the specimens was used the recommended etching time, the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and the shear bond strengths （SBS） were measured. Debonded surfaces were ob- served by scanning electron microscopy. Results In the etch-and-rinse adhesive system and one-step self-etching adhesive system, there was no significant difference between the recom- mended etching time and half of the time （ P 〉 0. 05 ）. In the two-step self-etching adhesive system, SBS of the recommended etching time group was higher than half of the time group （P 〈0. 05）, was also the highest among six groups. SEM observation showed that adhesive/ mixed failure were the most common type of every group that went through the tests. In the etch-and-rinse system, fracture were located at the top of the mixed layer. In the one-step self- etching system, most of dentinal tubules were empty. For the two-step self-etching system, res- in was adhered tightly to collagenous fiber. Conclusion In the etch-and-rinse adhesive system and the one-step self-etching adhesive system, shorting etching time is recommended, but in the two-step self-etching adhesive system, using the recommended etching time to get higher SBS.