Objective

To investigate the effect of blue light photoactivated riboflavin modified universal adhesives on dentin collagen biodegradation resistance, dentin apparent elastic modulus, and resin-dentin bond strength with interfacial morphology.

Methods

Dentin slabs were treated with 0.1% riboflavin-5-phosphate modified (powder added slowly while shaking and then sonicated to enhance the dispersion process) Universal Adhesive Scotch Bond and Zipbond™ along with control (non-modified) and experimental adhesives, photoactivated with blue light for 20s. Hydroxyproline (HYP) release was assessed after 1-week storage. Elastic-modulus testing was evaluated using universal testing machine at 24 h. Resin-dentin interfacial morphology was assessed with scanning electron-microscope, after 6-month storage. 0.1% rhodamine dye was added into each adhesive and analyzed using CLSM. Detection of free amino groups was carried out using ninhydrin and considered directly proportional to optical absorbance. Collagen molecular confirmation was determined using spectropolarimeter to evaluate and assess CD spectra. For molecular docking studies with riboflavin (PDB ID file), the binding pocket was selected with larger SiteScore and DScore using Schrodinger PB software. After curing, Raman shifts in Amide regions were obtained at 8 μm levels. Data were analyzed using Two-way analysis of variance (ANOVA, p ≤ 0.05) and Tukey–Kramer multiple comparison post hoc tests.

Results

At baseline, bond strength reduced significantly (p ≤ 0.05) in control specimens. However, at 6 months’ storage, UVA Zipbond™ had significantly higher μTBS. Resin was able to diffuse through the porous demineralized dentin creating adequate hybrid layers in both 0.1%RF modified adhesives in CLSM images. In riboflavin groups, hybrid layer and resin tags were more pronounced. The circular dichroism spectrum showed negative peaks for riboflavin adhesive specimens. Best fitted poses adopted by riboflavin compound are docked with MMP-2 and -9 proteases. Amide bands and CH₂ peaks followed the trend of being lowest for control UA Scotch bond adhesive specimens and increasing in Amides, proline, and CH₂ intensities in 0.1%RF modified adhesive specimens. All 0.1%RF application groups showed statistically significant (p < 0.05) less levels of HYP released compared to controls. Dentin E_appr of riboflavin application was significantly (p < 0.05) more as compared to control groups.

Conclusion

Blue light photoactivated 0.1% riboflavin modified adhesives improved the biochemical and biomechanical properties of demineralized dentin as well as the long-term resin-dentin interfacial integrity and bond strength of universal adhesive to dentin.

中文翻译：

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实验通用胶中掺入的光活化核黄素的多尺度体外分析

目的

目的研究蓝光光活化核黄素改性通用胶粘剂对牙本质胶原蛋白的抗生物降解性，牙本质表观弹性模量以及具有界面形态的树脂-牙本质结合强度的影响。

方法

牙本质板用0.1％核黄素5磷酸酯改性处理（在摇动的同时缓慢添加粉末，然后超声处理以增强分散过程）Universal Adhesive Scotch Bond和Zipbond™以及对照（未改性）和实验粘合剂，用蓝色光活化点亮20秒。储存1周后评估羟脯氨酸（HYP）的释放。弹性模量测试是在24小时内使用通用测试机进行评估的。保存六个月后，用扫描电子显微镜评估树脂-牙本质的界面形态。将0.1％罗丹明染料添加到每种粘合剂中，并使用CLSM分析。游离氨基的检测使用茚三酮进行，并被认为与吸光度成正比。使用分光旋光计确定胶原蛋白分子的确认，以评估和评估CD光谱。对于使用核黄素（PDB ID文件）进行的分子对接研究，使用Schrodinger PB软件使用较大的SiteScore和DScore选择结合口袋。固化后，酰胺区域的拉曼位移为8μm。使用双向方差分析（ANOVA，p≤0.05）和Tukey–Kramer多重比较事后检验分析数据。

结果

在基线时，对照样品的粘结强度显着降低（p≤0.05）。但是，在储存6个月后，UVA Zipbond™的μTBS明显更高。树脂能够通过多孔的脱矿质牙本质扩散，从而在CLSM图像的两种0.1％RF改性的粘合剂中形成足够的杂化层。在核黄素组中，杂化层和树脂标签更为明显。圆二色性光谱显示核黄素胶粘剂样品为负峰。核黄素化合物采用的最佳配合姿势与MMP-2和-9蛋白酶对接。酰胺带和CH ₂峰遵循以下趋势：对照UA苏格兰胶粘剂标本最低，酰胺，脯氨酸和CH _2增加0.1％RF改性的胶粘剂样品的强度。 与对照组相比，所有0.1％RF施用组的HYP释放水平均具有统计学意义（p <0.05）少。 与对照组相比，应用核黄素的Dentin E _appr显着多（p <0.05）。

结论

蓝光光活化0.1％核黄素改性粘合剂改善了脱矿牙本质的生化和生物力学性能，以及通用粘合剂与牙本质的长期树脂-牙本质界面完整性和粘合强度。