Hydrolytic and enzymatic degradation by matrix metalloproteinases (MMPs) reduces the durability of composite resin restorations on caries-affected dentin (CAD). The use of MMP inhibitors such as epigallocatechin-3-gallate (EGCG) could increase the longevity of the bond to dentin. This study aimed to evaluate the use of EGCG at different aqueous concentrations on the resin-dentin microtensile bond strength (μTBS), fracture pattern and nanoleakage (NL) in immediate (IM) time interval and after 12-months of water storage (1Y) when using a two-step etch-and-rinse adhesive system on CAD. Dentin surfaces of 40 human molars were submitted to a microbiological caries induction protocol and randomized into 5 groups (n = 8) (0.02% EGCG; 0.2% EGCG; 0.5% EGCG; 2% Chlorhexidine [CHX] and no treatment as Control Group - [NT]). After acid etching, the solutions were applied for 60 s followed by application of dental adhesive (Adper Single Bond 2, 3 M ESPE) to CAD surfaces. Subsequently, a resin composite (4 mm) block was built on the dentin. After 24 h, the teeth were sectioned into beam-shaped specimens (cross-sectional area of 1 mm² and 8-mm high). Half of the specimens were tested in IM and the other half after 1Y. Two samples per tooth were submitted to SEM for NL evaluation. Data were statistically analyzed by two-way ANOVA and Tukey tests (α = 0.05). The results showed that use of EGCG and CHX did not affect μTBS in IM (p > 0.05). After 1Y, there was a reduction in μTBS for all experimental groups (p < 0.05). Adhesive fractures predominated in IM in all groups, except for 0.05% EGCG and NT. After 1Y, there was an increase in these adhesive fractures in all groups. For NL, all agents applied reduced NL in comparison with CT (p < 0.001). CHX showed lower NL (p < 0.001), followed by 0.02% and 0.5% EGCG. NT showed highest NL for both time intervals (p < 0.001). Thus, although the use of EGCG at different concentrations and CHX reduced the NL, they were unable to reduce degradation of μTBS to CAD over time.

基质金属蛋白酶（MMP）的水解和酶促降解降低了龋齿影响的牙本质（CAD）上复合树脂修复体的耐用性。使用MMP抑制剂，例如表没食子儿茶素-3-没食子酸酯（EGCG）可以增加与牙本质的键的寿命。这项研究旨在评估不同浓度的EGCG在立即（IM）时间间隔和储水12个月（1Y）后对树脂-牙本质微拉伸键强度（μTBS），断裂模式和纳米泄漏（NL）的使用情况在CAD上使用两步蚀刻和冲洗粘合系统时。将40个人类磨牙的牙本质表面进行微生物龋齿诱导方案处理，并随机分为5组（n = 8）（0.02％EGCG； 0.2％EGCG； 0.5％EGCG； 2％洗必泰[CHX]），并且未作为对照组进行治疗- [NT]）。酸蚀后 将该溶液施涂60 s，然后在CAD表面施涂牙科粘合剂（Adper Single Bond 2、3 M ESPE）。随后，在牙本质上构建树脂复合材料（4毫米）块。24小时后，将牙齿切成梁形样本（横截面积为1 mm^2个和8毫米高）。一半的样品在IM中测试，另一半在1年后测试。每颗牙齿有两个样品送至SEM进行NL评估。数据通过双向方差分析和Tukey检验进行统计分析（α= 0.05）。结果表明，使用EGCG和CHX不会影响IM中的μTBS（p> 0.05）。1年后，所有实验组的μTBS均降低（p <0.05）。除0.05％EGCG和NT外，所有组的IM均以胶粘剂骨折为主。1年后，所有组的这些粘合剂断裂均增加。对于NL，与CT相比，所有药物应用的NL均减少（p <0.001）。CHX显示较低的NL（p <0.001），其次是0.02％和0.5％EGCG。NT在两个时间间隔内均显示出最高的NL（p <0.001）。因此，尽管使用不同浓度的EGCG和CHX可以降低NL，