Purpose

To assess the effect of dicalcium phosphate dihydrate (DCPD) or mineral trioxide aggregate (MTA) particles on the microtensile bond strength (μTBS), micro-permeability and enzymatic activity at the adhesive-dentin interface of experimental dental adhesives.

Materials and methods

An experimental ethanol-based, two-step etch-and-rinse adhesive system was prepared. Four experimental groups were tested, based on the type of particle added: (1) DCPD functionalized with diethylene glycol dimethacrylate (DCPD_DEGDMA), (2) citric acid (DCPD_CA), (3) calcium silicate (MTA) and (4) unfilled (control). All particles were added at 10 wt%. Human third molars had their occlusal enamel removed and dentin surface polished. After acid etching, the adhesives were applied on the dentin surfaces and the teeth were restored with a commercial nanofilled resin composite. The μTBS and micro-permeability were tested after 24 h or 2 months of storage in simulated body fluid (SBF) at 37 °C. Bonded interfaces were observed using scanning electron microcopy (SEM). Gelatinolytic activity at the adhesive interfaces was assessed by in situ zymography at 24 h and 2 months in SBF/37 °C. The results were described as relative florescent units (RFU). μTBS data were analyzed by ANOVA/Games–Howell test. Data from micro-permeability and in situ zymography were analyzed by Kruskal–Wallis/Mann–Whitney test (alpha: 5%).

Results

Differences in μTBS were found among adhesives (control = MTA > DCPD_CA > DCPD_DEGDMA, p < 0.001), but not between storage times. The control group showed the lowest permeability at both observation periods. Except for DCPD_CA, no significant increases in micro-permeability were observed after 2 months. All groups presented significant reductions in RFU values between 24 h and 2 months. DCPD_DEGDMA (at 24 h) and MTA (at 2 months) presented statistically lower RFU than the control (p < 0.01).

Conclusion

Evidence of reduced MMP activity was observed at adhesive interfaces with the use of experimental adhesives containing calcium-releasing particles. However, after two months, bond strength and micro-permeability results suggest that interfacial stability was not affected by adhesive formulation.

中文翻译：

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含有正磷酸钙颗粒的实验性牙本质粘合剂：对牙本质粘合强度，微渗透性和胶原蛋白降解的影响

目的

为了评估二水合磷酸二钙（DCPD）或三氧化二矿物聚集体（MTA）颗粒对实验牙科用胶粘剂与牙本质界面处的微拉伸粘合强度（μTBS），微渗透性和酶活性的影响。

材料和方法

制备了实验性的基于乙醇的两步蚀刻和漂洗胶粘剂系统。根据添加的颗粒类型测试了四个实验组：（1）用二甘醇二甲基丙烯酸二甲酯（DCPD_DEGDMA）功能化的DCPD，（2）柠檬酸（DCPD_CA），（3）硅酸钙（MTA）和（4）未填充的（控制）。所有颗粒均以10重量％添加。人类的第三臼齿的牙釉质被去除，牙本质表面被抛光。酸蚀后，将粘合剂涂在牙本质表面上，并用市售的纳米填充树脂复合材料修复牙齿。在37°C的模拟体液（SBF）中存储24小时或2个月后，测试了μTBS和微渗透率。使用扫描电子显微镜（SEM）观察键合的界面。在胶粘剂界面的明胶分解活性通过SBF / 37°C下24 h和2个月时进行原位酶谱分析。结果描述为相对荧光单位（RFU）。μTBS数据通过ANOVA / Games-Howell检验进行了分析。通过Kruskal–Wallis / Mann–Whitney检验（α：5％）分析了微渗透率和原位酶谱数据。

结果

在粘合剂之间发现了μTBS的差异（对照= MTA> DCPD_CA> DCPD_DEGDMA，p <0.001），但在存储时间之间没有差异。对照组在两个观察期均显示出最低的渗透率。除DCPD_CA外，两个月后未观察到微渗透率的显着增加。所有组均显示24小时至2个月内RFU值显着降低。DCPD_DEGDMA（24小时）和MTA（2个月）的RFU在统计学上低于对照组（p <0.01）。

结论

使用含有释放钙的颗粒的实验胶粘剂，在胶粘剂界面处观察到MMP活性降低的证据。但是，两个月后，粘合强度和微渗透率结果表明界面稳定性不受粘合剂配方的影响。