Objective

As frequently added to adhesives, the mono-functional monomer 2-hydroxyethyl methacrylate (HEMA) acts as co-solvent and improves surface wetting. Nevertheless, HEMA promotes watersorption and hydrolysis at adhesive interfaces, affecting bond durability to dentin. This study investigated if two acrylamide co-monomer alternatives could replace HEMA in experimental adhesive-resin formulations as part of 3/2-step universal adhesives applied, respectively, in etch-and-rinse (E&R) and self-etch (SE) bonding modes.

Methods

Upon priming dentin with the 10-MDP-based Clearfil SE Bond 2’ primer (‘C-SE2p’; Kuraray Noritake), three experimental adhesive resins, consisting of 50 wt.% Bis-GMA, 15 wt.% TEGDMA, and either 35 wt.% diethyl acrylamide (‘DEAA’), hydroxyethyl acrylamide (‘HEAA’) or HEMA (‘HEMA+’), were applied. The control HEMA-free adhesive resin contained 60 wt.% Bis-GMA and 40 wt.% TEGDMA (‘HEMA−’). All adhesives were evaluated for ‘immediate’ and ‘aged’ micro-tensile bond strength (μTBS) to dentin upon, respectively, 1-week (1w) and 6-month (6m) water storage, TEM adhesive-dentin interfacial interaction, 24-h and 6m three-point bending, contact-angle wetting, viscosity and watersorption.

Results

Linear mixed-effects model statistics revealed significantly better bonding performance of the adhesives applied in E&R than SE mode, except for DEAA_1w, with the highest μTBSs recorded for DEAA and HEMA− applied in SE mode. In E&R mode, aging did not significantly reduce DEAA’s μTBS. Best wetting on primed dentin was recorded for HEMA+, significantly better than DEAA, further HEAA and HEMA−, these directly related to their viscosity. HEAA absorbed significantly more water than all other adhesive-resin formulations. HEMA−>DEAA>HEAA>HEMA+ was the significant order for 6m bending strength.

Conclusions

The acrylamide co-monomer DEAA could replace HEMA, while HEAA not.

中文翻译：

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两步胶中丙烯酰胺HEMA替代单体的多参数评估

目的

如经常添加到粘合剂中的那样，单官能单体甲基丙烯酸2-羟乙酯（HEMA）用作助溶剂并改善表面润湿性。然而，HEMA促进了粘合剂界面的吸水和水解，影响了与牙本质的粘合耐久性。这项研究调查了两种丙烯酰胺共聚单体替代物是否可以代替实验胶粘剂配方中的HEMA，作为分别用于蚀刻和冲洗（E＆R）和自蚀刻（SE）粘合的3/2步骤通用胶粘剂的一部分模式。

方法

用基于10-MDP的Clearfil SE Bond 2'底漆（'C-SE2p'; Kuraray Noritake）涂上牙本质后，三种实验粘合树脂，分别由50 wt％的Bis-GMA，15 wt％的TEGDMA和施加35重量％的二乙基丙烯酰胺（'DEAA'），羟乙基丙烯酰胺（'HEAA'）或HEMA（'HEMA +'）。不含HEMA的对照胶粘树脂包含60％（重量）的Bis-GMA和40％（重量）的TEGDMA（'HEMA-'）。分别在1周（1w）和6个月（6m）的储水量，TEM粘合剂与牙本质的界面相互作用，24时评估所有粘合剂与牙本质的“即时”和“老化”微拉伸粘合强度（μTBS）24 -h和6m三点弯曲，接触角润湿，粘度和吸水率。

结果

线性混合效应模型统计数据表明，除DEAA_1w以外，在E＆R中使用的胶粘剂的粘合性能明显优于SE模式，在SE模式下使用DEAA和HEMA-记录的μTBS最高。在E＆R模式下，老化不会显着降低DEAA的μTBS。记录的针对底漆牙本质的最佳润湿性对于HEMA +而言，明显优于DEAA，进一步优于HEAA和HEMA-，这些都与它们的粘度直接相关。与所有其他粘合剂树脂配方相比，HEAA吸收的水分明显更多。HEMA-> DEAA> HEAA> HEMA +是6m抗弯强度的重要顺序。

结论

丙烯酰胺共聚单体DEAA可以代替HEMA，而HEAA不能。