Objectives

To investigate the role of proteoglycans (PGs) on the physical properties of the dentin matrix and the bond strength of methacrylate resins with varying hydrophilicities.

Methods

Dentin were obtained from crowns of human molars. Enzymatic removal of PGs followed a standard protocol using 1 mg/mL trypsin (Try) for 24 h. Controls were incubated in ammonium bicarbonate buffer. Removal of PGs was assessed by visualization of glycosaminoglycan chains (GAGs) in dentin under transmission electron microscopy (TEM). The dentin matrix swelling ratio was estimated using fully demineralized dentin. Dentin wettability was assessed on wet, dry and re-wetted dentin surfaces through water contact angle measurements. Microtensile bond strength test (TBS) was performed with experimental adhesives containing 6% HEMA (H₆) and 18% HEMA (H₁₈) and a commercial dental adhesive. Data were statistically analyzed using ANOVA and post-hoc tests (α = 0.05).

Results

The enzymatic removal of PGs was confirmed by the absence and fragmentation of GAGs. There was statistically significant difference between the swelling ratio of Try-treated and control dentin (p < 0.001). Significantly lower contact angle was found for Try-treated on wet and dry dentin (p < 0.002). The contact angle on re-wet dentin was not recovered in Try-treated group (p = 0.9). Removal of PGs significantly improved the TBS of H₆ (109% higher, p < 0.001) and H₁₈ (29% higher, p = 0.002) when compared to control. The TBS of commercial adhesive was not affected by trypsin treatment (p = 0.9).

Significance

Changing the surface energy of dentin by PGs removal improved resin adhesion, likely due to more efficient water displacement, aiding to improved resin infiltration and polymerization.

中文翻译：

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从牙本质中去除水结合蛋白可提高低亲水性牙科树脂的粘合强度。

目标

研究蛋白聚糖（PGs）在牙本质基质的物理性质和具有不同亲水性的甲基丙烯酸酯树脂的粘结强度上的作用。

方法

牙本质是从人类臼齿的牙冠获得的。遵循标准规程，使用1 mg / mL胰蛋白酶（Try）酶解PG，持续24 h。将对照在碳酸氢铵缓冲液中孵育。通过在透射电子显微镜（TEM）下观察牙本质中的糖胺聚糖链（GAG）来评估PG的去除。使用完全脱矿质的牙本质估计牙本质基质的溶胀率。通过水接触角测量来评估在湿润，干燥和重新润湿的牙本质表面上的牙本质润湿性。用包含6％HEMA（H ₆）和18％HEMA（H ₁₈）的实验性粘合剂和市售牙科粘合剂进行微拉伸粘合强度测试（TBS）。使用方差分析和事后检验对数据进行统计分析（α= 0.05）。

结果

通过GAG的缺失和断裂证实了PG的酶促去除。尝试治疗和对照牙本质的溶胀率之间存在统计学差异（p <0.001）。在湿式和干式牙本质上进行Try-处理后，发现其接触角明显较低（p <0.002）。在Try-治疗组中，未恢复湿润牙本质上的接触角（p = 0.9）。与对照组相比，PG的去除显着改善了H ₆（高109％，p <0.001）和H ₁₈（高29％，p = 0.002）的TBS 。商业胶粘剂的TBS不受胰蛋白酶处理的影响（p = 0.9）。

意义

通过PG的去除改变牙本质的表面能可改善树脂的附着力，这可能是由于更有效的水置换作用，有助于改善树脂的渗透和聚合作用。