Abstract The microtensile bond strength (μTBS), nanoleakage expression (NL), and endogenous enzymatic activity of a simplified universal adhesive system used in combination with a dual-cure resin cement for luting indirect restorations were evaluated considering its shelf-life (as-received vs expired). The universal adhesive was used as-received (AS-R) by manufacturer or after three months after being expired (EXP). Resin composite overlays (n = 10) were luted to flat deep coronal dentin surfaces with a universal bonding system (iBond universal, used in the self-etch mode) in combination with a dual-cure resin cement (RelyX Ultimate; 20s of light-cure followed by 15 min of self-cure at 37 °C). After 24 h, the specimens were cut into microtensile sticks (1 mm2) and stressed to failure under tension, in accordance with ISO/TS 11.405. The fracture pattern was evaluated with optical microscopy. The significance level of p = 0.05 was used for the statistical analysis. Additional specimens (n = 4) were processed for quantitative interfacial nanoleakage expression using ammoniacal silver nitrate. To investigate the endogenous enzymatic activity within the hybrid layer in situ zymography was performed. The EXP group obtained significantly lower μTBS values than those recorded in the AS-R group (p

中文翻译：

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通用粘合剂对牙本质的保质期的影响

摘要 考虑其保质期（原样），评估了一种简化的通用粘合剂系统与双固化树脂水门汀结合用于间接修复的微拉伸粘合强度 (μTBS)、纳米渗漏表达 (NL) 和内源性酶活性。 vs 过期）。通用粘合剂由制造商按原样 (AS-R) 或在过期三个月后 (EXP) 使用。树脂复合材料覆盖层（n = 10）使用通用粘合系统（iBond 通用，用于自蚀刻模式）结合双固化树脂水门汀（RelyX Ultimate；20 秒的光-固化，然后在 37 °C 下自固化 15 分钟）。24 小时后，根据 ISO/TS 11.405，将试样切成微拉伸棒 (1 mm2) 并在张力下受力破坏。用光学显微镜评估断裂模式。p = 0.05 的显着性水平用于统计分析。使用氨硝酸银处理其他样本 (n = 4) 以进行定量界面纳米渗漏表达。为了研究杂合层内的内源酶活性，进行了原位酶谱分析。EXP 组获得的 μTBS 值明显低于 AS-R 组（p