2种脱敏剂对牙本质表面微结构及聚羧酸锌水门汀剪切强度的影响

The effects of two desensitizing agents on the microstructure of dentin surface and the shear bond strength of poly carboxylic zinc cement to tooth

目的:评价2种脱敏剂对牙本质表面微结构及聚羧酸锌水门汀粘接剂剪切强度的影响。方法:将36颗离体前磨牙用圆柱形模具包埋在自凝树脂中,使颊面暴露。高速手机去除颊面釉质,并用水砂纸流水下磨平。将36颗离体牙用随机数字表分为3组(n=12):A组样本为对照不作处理,B组样本用氟保护漆,C组样本用Oravive,按操作要求涂布牙本质表面后,每组随机选取3个样本进行电镜观察,其余用聚羧酸锌水门汀粘接剂粘接直径4 mm、厚为2 mm的钴铬合金试件,进行剪切试验,体视显微镜下观察离断面类型。结果:扫描电镜观察显示脱敏后的牙本质小管口有不同程度的微粒阻塞物。剪切强度(MPa)测试A、B、C组分别为:3.986±0.374、3.646±0.236和4.674±0.426;A组与B组比较P>0.05,A组、B组分别与C组比较P<0.05。离断面类型多为粘接剂内聚破坏。结论:在本实验条件下,氟保护漆对聚羧酸锌水门汀的剪切强度无明显影响;Oravive能增强聚羧酸锌水门汀的剪切强度。

Objective： To study the effects of 2 desensitizing agents on the microstructure of the dentin surface and the shear bond strength of poly carboxylic zinc cement to dentin. Methods： 36 extracted human premolars were embedded in acrylic resin using cus- tom made cylinder-shaped molds except the buccal surface, the enamel of the buccal surface was removed with a diamond saw, dentin surface was polished with waterproof polishing papers to create standardized surface. 36 premolars were divided into 3 groups with ran- dom digital table method （n = 12）. Samples in group A were not treated as the controls, those in group B and C were treated with flu- oride protector and Oravive respectively. 3 samples of every group were randomly chosen and examined by SEM. The rest of the speci- mens were then bonded to Cobalt chromium alloy casting with a diameter and height of 4 mm and 2 mm respectively. The shear bond strength of the specimens was measured. The fracture pattern was examined by stereomicroscope. Results： Scanning electron microsco- py showed small particles in the dentinal tubules after desensitizing treatment. The shear bond strength （MPa） of group A, B and C was 3. 986 ± O. 374, 3. 646 ±O. 236 and 4.674 ± 0. 426 resoectively; A vs B,P 〉 0.05, A or B vs C, P 〈 0.05. Most of the fracture pattern was cement cohesive failure. Conclusion： Fluoride protector does not affect the strength of poly carboxylic zinc cement to den- tin, Oravive can enhance the strength.