Objectives

To develop a protocol for assessment of the bulk viscoelastic behavior of dentin extracellular matrix (ECM), and to assess relationships between induced collagen cross-linking and viscoelasticity of the dentin ECM.

Methods

Dentin ECM was treated with agents to induce exogenous collagen cross-linking: proanthocyanidins (PACs) from Vitis vinifera – VVe, PACs from Pinus massoniana - PMe, glutaraldehyde – (GA), or kept untreated (control). A dynamic mechanical strain sweep method was carried out in a 3-point bending submersion clamp at treatment; after protein destabilization with 4 M urea and after 7-day, 6-month, and 12-month incubation in simulated body fluid. Tan δ, storage (E’), loss (E”), and complex moduli (E*) were calculated and data were statistically analyzed using two-way ANOVA and post-hoc tests (α = 0.05). Chemical analysis of dentin ECM before and after protein destabilization was assessed with ATR-FTIR spectroscopy.

Results

Significant interactions between study factors (treatment vs. time points, p < 0.001) were found for all viscoelastic parameters. Despite a significant decrease in all moduli after destabilization, PAC-treated dentin remained statistically higher than control (p < 0.001), indicating permanent mechanical enhancement after biomodification. Covalently crosslinked, GA-treated dentin was unaffected by destabilization (p = 0.873) and showed the lowest damping capacity (tan δ) at all time points (p < 0.001). After 12 months, the damping capacity of PMe and VVe groups decreased significantly. Changes in all amide IR resonances revealed a partial chemical reversal of PAC-mediated biomodification.

Significance

Viscoelastic measurements and IR spectroscopy aid in elucidating the role of inter-molecular collagen cross-linking in the mechanical behavior of dentin ECM.

中文翻译：

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一种评估牙本质细胞外基质整体粘弹性行为的动态力学方法

目标

制定评估牙本质细胞外基质 (ECM) 的大量粘弹性行为的协议，并评估诱导的胶原交联与牙本质 ECM 的粘弹性之间的关系。

方法

牙本质 ECM 用试剂处理以诱导外源性胶原交联：来自葡萄的原花青素 (PAC) - VVe、来自马尾松的PAC - PMe、戊二醛 - (GA)，或保持未经处理（对照）。治疗时在三点弯曲浸入式夹具中进行动态机械应变扫描法；用 4 M 尿素使蛋白质不稳定并在模拟体液中孵育 7 天、6 个月和 12 个月后。计算了 Tan δ、存储 (E')、损失 (E") 和复模量 (E*)，并使用双向方差分析和事后检验 (α = 0.05) 对数据进行了统计分析。用 ATR-FTIR 光谱评估蛋白质去稳定前后牙本质 ECM 的化学分析。

结果

对于所有粘弹性参数，发现研究因素（治疗对时间点，p < 0.001）之间的显着相互作用。尽管去稳定后所有模量均显着降低，但 PAC 处理的牙本质在统计学上仍高于对照（p < 0.001），表明生物改性后的机械性能得到永久性增强。共价交联的 GA 处理的牙本质不受不稳定的影响 (p = 0.873)，并且在所有时间点都显示出最低的阻尼能力 (tan δ) (p < 0.001)。12个月后，PMe和VVe组的阻尼能力显着下降。所有酰胺红外共振的变化揭示了 PAC 介导的生物修饰的部分化学逆转。

意义

粘弹性测量和红外光谱有助于阐明分子间胶原交联在牙本质 ECM 机械行为中的作用。