Objectives

Hydroxyethyl-methacrylate (HEMA) is still widely used in simplified adhesives. Indeed, several shortcomings occur with this monomer, such as water uptake and formation of linear polymers. This study aimed to compare the effects of HEMA replacement by glycerol-dimethacrylate (GDMA) on selected physicochemical properties and bonding performance of simplified model adhesives.

Materials and Methods

Experimental simplified etch-and-rinse and self-etch adhesives were formulated containing 20 wt% HEMA or GDMA. Three-point bending test was used to obtain the elastic modulus of bar-shaped specimens, and water sorption and solubility were attained by ISO-4049 (ISO, 2009) method. Degree of conversion was surveyed by Micro-Raman spectroscopy, and microtensile bond strength was tested after 24 h or 6 months simulated pulpal pressure aging. Statistical analysis was realized with two-way ANOVA and Tukey's test (p < 0.05).

Results

GDMA promoted higher elastic modulus to the self-etch adhesive, and GDMA-containing etch-and-rinse adhesive achieved overall lower water sorption and solubility. The degree of conversion was statistically higher for GDMA adhesives than for HEMA etch-and-rinse one. All bond strengths dropped significantly after aging, except that of GDMA self-etch adhesive. The nanoleakage was higher and gaps were found in the interface of HEMA-containing adhesives, which were less present in GDMA equivalents.

Conclusions

GDMA is a feasible hydrophilic dimethacrylate monomer to replace HEMA in simplified adhesives, thereby providing better polymerization, mechanical properties and dentin adhesion as well as lower water uptake and solubility.

中文翻译：

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甘油-二甲基丙烯酸酯作为替代的亲水性单体，用于简化胶粘剂中的HEMA替代

目标

甲基丙烯酸羟乙酯（HEMA）仍广泛用于简化粘合剂中。实际上，该单体存在一些缺点，例如吸水和线性聚合物的形成。这项研究旨在比较甘油二甲基丙烯酸酯（GDMA）替代HEMA对简化模型胶粘剂的选定理化性质和粘合性能的影响。

材料和方法

配制了包含20 wt％HEMA或GDMA的实验性简化蚀刻和冲洗和自蚀刻粘合剂。使用三点弯曲试验获得棒状样品的弹性模量，并通过ISO-4049（ISO，2009）方法获得吸水率和溶解度。通过显微拉曼光谱法测量转化度，并且在模拟的纸浆压力老化24小时或6个月后测试微拉伸粘合强度。采用双向方差分析和Tukey检验实现统计分析（p <0.05）。

结果

GDMA促进了自蚀刻胶粘剂的更高弹性模量，而含GDMA的蚀刻和冲洗胶粘剂总体上降低了水的吸收性和溶解性。从统计上来说，GDMA胶粘剂的转化程度要高于HEMA蚀刻和漂洗胶粘剂的转化程度。老化后，所有粘合强度均显着下降，但GDMA自蚀刻胶粘剂除外。纳米泄漏较高，并且在含HEMA的胶粘剂界面中发现了缝隙，在GDMA等效物中较少出现缝隙。

结论

GDMA是一种可行的亲水性二甲基丙烯酸酯单体，可以代替HEMA简化粘合剂，从而提供更好的聚合，机械性能和牙本质粘合力，并降低吸水率和溶解度。