Objective

Imperfect polymer formation as well as collagen’s susceptibility to enzymatic degradation increase the vulnerability of hybrid layers over time. This study investigated the effect of new dimethyl sulfoxide (DMSO)-containing pretreatments on long-term bond strength, hybrid layer quality, monomer conversion and collagen structure.

Methods

H₃PO₄-etched mid-coronal dentin surfaces from extracted human molars (n = 8) were randomly treated with aqueous and ethanolic DMSO solutions or following the ethanol-wet bonding technique. Dentin bonding was performed with a three-step etch-and-rinse adhesive. Resin-dentin beams (0.8 mm²) were stored in artificial saliva at 37 °C for 24 h and 2.5 years, submitted to microtensile bond strength testing at 0.5 mm/min and semi-quantitative SEM nanoleakage analysis (n = 8). Micro-Raman spectroscopy was used to determine the degree of conversion at different depths in the hybrid layer (n = 6). Changes in the apparent modulus of elasticity of demineralized collagen beams measuring 0.5 × 1.7 × 7 mm (n = 10) and loss of dry mass (n = 10) after 30 days were calculated via three-point bending and precision weighing, respectively.

Results

DMSO-containing pretreatments produced higher bond strengths, which did not change significantly over time presenting lower incidence of water-filled zones. Higher uniformity in monomer conversion across the hybrid layer occurred for all pretreatments. DMSO-induced collagen stiffening was reversible in water, but with lower peptide solubilization.

Significance

Improved polymer formation and higher stability of the collagen-structure can be attributed to DMSO’s unique ability to simultaneously modify both biological and resin components within the hybrid layer. Pretreatments composed of DMSO/ethanol may be a viable-effective alternative to extend the longevity of resin-dentin bonds.

中文翻译：

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追求树脂-牙本质键合耐久性：混合层中胶原结构和聚合物网络形成的同时增强

客观的

不完全的聚合物形成以及胶原蛋白对酶降解的敏感性随着时间的推移增加了混合层的脆弱性。本研究调查了新的含二甲基亚砜 (DMSO) 的预处理对长期粘合强度、杂化层质量、单体转化和胶原结构的影响。

方法

用含水和乙醇 DMSO 溶液或按照乙醇-湿粘合技术随机处理来自提取的人类臼齿 (n = 8) 的H ₃ PO _{4蚀刻的中冠状牙本质表面。}使用三步蚀刻和冲洗粘合剂进行牙本质粘合。树脂-牙本质束 (0.8 mm ² ) 在人工唾液中 37 °C 储存 24 小时和 2.5 年，以 0.5 mm/min 的速度进行微拉伸粘合强度测试和半定量 SEM 纳米泄漏分析 (n = 8)。微拉曼光谱用于确定混合层中不同深度的转换程度（n = 6）。计算 30 天后测量 0.5 × 1.7 × 7 mm (n = 10) 和干质量损失 (n = 10) 的脱矿质胶原束的表观弹性模量变化分别通过三点弯曲和精密称重。

结果

含有 DMSO 的预处理产生了更高的粘合强度，随着时间的推移没有显着变化，表明充水区的发生率较低。对于所有预处理，混合层上的单体转化率均较高。DMSO 诱导的胶原蛋白硬化在水中是可逆的，但肽溶解度较低。

意义

改进的聚合物形成和更高的胶原结构稳定性可归因于 DMSO 在混合层内同时修饰生物和树脂成分的独特能力。由 DMSO/乙醇组成的预处理可能是延长树脂-牙本质键寿命的可行有效替代方案。