中文摘要：

目的：观察在离体牙上循环加载对不同涂布次数下第七代粘结剂Easy One粘结强度的影响。方法：选择90个离体前磨牙制备标准I类洞型后,随机分3组,涂布1次（A组）、涂布2次（B组）、涂布3次（C组）,根据相应涂布次数处理后进行树脂充填。每组又随机分3组,无加载组（a组）、加载10000次组（b组）、加载60000次组（c组）。各组在加载后经薄片推出试验测定各组的粘结强度值。结果：各组的粘结强度值为：Aa（33.91±4.17）MPa,Ab（30.93±4.47）MPa,Ac（22.82±4.68）MPa,Ba（35.73±4.35）MPa,Bb（32.40±4.43）MPa,Bc（24.13±4.59）MPa,Ca（28.15±4.30）MPa,Cb（24.85±4.70）MPa,Cc（16.61±4.66）MPa,相同的涂布次数条件下,加载60000次组界面的粘结强度明显小于加载10000次组或无加载组（P〈0.05）;相同的加载次数条件下,涂布3次的粘结界面强度小于涂布2次和涂布1次的粘结界面强度,差异具有统计学意义（P〈0.05）。结论：循环加载会使牙本质粘结剂的粘结强度下降;不同涂布次数中,涂布1次、2次的均能得到较为理想的粘结强度。

英文摘要：

Objective： To study the effect of cycling mechanical loading on the bond strength of the 7th dentin adhesion agent with different coating times. Methods： 90 fresh premolars that was extracted for Orthodontic reasons were selected prepared by the standard of Class - 1 hole type, and divided into 3 groups according to the coating times （A coating 1 time, B coating 2 times, C coating 3 times）. Then they were filled with resin restoration. Each group was randomly divided into 3 groups again, which is, one experimental group of a, cycling-loading 10000 times, one experimental group of b , cycling-loading 60000 times, one control group of c , non- cycling-loading. Then we determined the bond strength of each sample. Results： The bond strength of each group is Aa（33. 91±4. 17）MPa, Ab（30. 93±4. 47）MPa, Ac（22. 82±4. 68）MPa, Ba（35. 73±4. 35）MPa, Bb（32. 40±4. 43）MPa, Bc（24. 13±4. 59）MPa, Ca（28.15±4. 30）MPa, Cb（24. 85±4. 70）MPa, Cc（16. 61±4. 66）MPa; The bond strength in the group of cycling - loading 60000 times is obviously less than the group of cycling - loading 10000 times and the group of non - cycling-loading with coating same time （P〈0. 05）; the bond strength of the group coating 3 times is obviously decreased （P〈0. 05）. Conclusion： The bond strength of dentin adhesionagent reduces with the increase of cycling mechanical loading times. Better bond strength could be gained when coating 1 time or 2 times.