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目的研究G4.5带有羧基基团的聚酰胺-胺树枝状聚合物（PAMAM-COOH dendrimer）诱导牙本质再矿化和对牙本质基质金属蛋白酶（matrix metalloproteinases, MMPs）活性的作用。方法将牙本质样本平均分成4组，分别设为：A组（100 mg/mL PAMAM-COOH组），B组（10 mg/mL PAMAM-COOH组），C组〔2%（质量分数）氯己定（CHX）组〕，以及对照组（去离子水组）。采用MMP活性荧光测定试剂盒检测4组内源性MMPs活性；测定30 d牙本质样本干重损失量；原位酶谱法检测0 h和48 h各组（A组除外）对牙本质内源性明胶酶活性的影响；在人工唾液中孵育7 d及14 d后使用场发射扫描电镜观察各组（A组除外）牙本质表面再矿化。结果与对照组相比，A、B、C组牙本质内源性MMPs活性均降低（P<0.05）；C组牙本质内源性MMPs活性低于A、B组（P<0.001），但A组和B组之间差异无统计学意义。A、B、C组的干重变化都小于对照组（P<0.05），但A、B、C组间差异无统计学意义。原位酶谱法结果显示，与对照组相比，B组荧光强度在0 h与对照组相差不大，在48 h后能抑制牙本质内胶原酶，但抑制作用弱于CHX。7 d和14 d后，对照组未观察到明显矿化，而B组持续矿化，效果优于C组。结论G4.5 PAMAM-COOH能够在牙本质表面发挥双重作用，既能有效抑制脱矿牙本质中的内源性MMPs活性，又能诱导脱矿牙本质再矿化，具有增强牙本质粘接长效性的潜力。“,”ObjectiveThe purpose of this study was to investigate the effect of G4.5 carboxyl-terminated poly dendrimer (PAMAM-COOH) on the dentin remineralization and the matrix metalloproteinases (MMPs) activity.MethodsThe dentine samples were averagely divided into four groups: 100 mg/mL PAMAM-COOH group (A group), 10 mg/mL PAMAM-COOH group (B group), 2% (wt) chlorhexidine (CHX) group (C group) and deionized water group (Control group). MMP Activity Assay Kit was used to detect the activity of dentin endogenous MMPs in the four groups. The loss of dry mass of dentin after 30 d were measured. In situ zymography analysis was performed to detect the effects of PAMAM dendrimer in each group (except A group) on gelatinase activity in dentin. After incubation in artificial saliva for 7 and 14 d incubated, the remineralization of each group (except A group) in dentin surfaces were examined using a field emission-scanning electron microscope (FESEM).ResultsCompared with the control group, the dentin endogenous MMPs activity in A, B and C groups were all decreased (P<0.05). The activity of endogenous MMPs in C group was lower than that of A and B groups (P<0.001), but the difference between A and B groups was not statistically significant. The loss of dry mass in A, B and C groups were lower than that in control group (P<0.05), but there were no significant difference in A, B and C groups. The in situ zymography analysis showed that 48 h later, the dentin gelatinase activity in B group was inhibited compared with the control group, but the inhibitory effect was weaker than that of CHX. After 7 d and 14 d, there were no obvious mineralization in the control group, while distinct mineralization were observed in B group. The mineralization effect in group B was better than group C.ConclusionG4.5 PAMAM-COOH could introduce remineralizationin and demineralizeddentin by effectively inhibiting endogenous MMPs and gelatinase, thus contributes as novel material to enhancing durability of adhesion.