Department of Operative Dentistry, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Maximo s/n, 18071, Granada, Spain.
Department of Geology, Faculty of Geology, University of Oviedo, Jesús Arias de Velasco s/n, 33005, Oviedo, Spain.
Clin Oral Investig. 2021 Mar;25(3):841-849. doi: 10.1007/s00784-020-03371-9. Epub 2020 May 27.
This study compared the chemical composition, microstructural, and mechanical properties of human and bovine dentin subjected to a demineralization/remineralization process.
Human and bovine incisors were sectioned to obtain 120 coronal dentin beams (6 × 1 × 1 mm) that were randomly allocated into 4 subgroups (n = 15) according to the time of treatment (sound, pH-cycling for 3, 7, and 14 days). Three-point bending mechanical test, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric (TG), and X-ray diffraction (XRD) techniques were employed to characterize the dentin samples.
Regarding chemical composition at the molecular level, bovine sound dentin showed significantly lower values in organic and inorganic content (collagen cross-linking, CO/amide I, and CO/PO; p = 0.002, p = 0.026, and p = 0.002, respectively) compared to humans. Employing XRD analyses, a higher mineral crystallinity in human dentin than in bovines at 7 and 14 days (p = 0.003 and p = 0.009, respectively) was observed. At the end of the pH-cycling, CI (ATR-FTIR) and CO/PO ratios (ATR-FTIR) increased, while CO/amide I (ATR-FTIR), PO/amide I (ATR-FTIR), and %mineral (TG) ratios decreased. The extension by compression values increased over exposure time with significant differences between dentin types (p < 0.001, in all cases), reaching higher values in bovine dentin. However, flexural strength (MPa) did not show differences between groups. We also observed the correlation between compositional variables (i.e., PO/amide I, CI, and %mineral) and the extension by compression.
Human and bovine dentin are different in terms of microstructure, chemical composition, mechanical strength, and in their response to the demineralization/remineralization process by pH-cycling.
These dissimilarities may constitute a potential limitation when replacing human teeth with bovines in in vitro studies.
本研究比较了经历脱矿/再矿化过程的人牙和牛牙的化学成分、微观结构和力学性能。
将人牙和牛牙的切牙部分切成 120 个冠部牙本质梁（6×1×1mm），根据处理时间（正常、pH 循环 3、7 和 14 天）将其随机分为 4 组（每组 15 个样本）。采用三点弯曲力学试验、衰减全反射傅里叶变换红外光谱（ATR-FTIR）、热重分析（TG）和 X 射线衍射（XRD）技术对牙本质样本进行表征。
就分子水平上的化学成分而言，与人类相比，牛牙正常牙本质的有机和无机含量（胶原交联、CO/酰胺 I 和 CO/PO）明显较低（p=0.002、p=0.026 和 p=0.002）。通过 XRD 分析，在 7 天和 14 天观察到人牙本质的矿物质结晶度明显高于牛牙本质（p=0.003 和 p=0.009）。在 pH 循环结束时，CI（ATR-FTIR）和 CO/PO 比值（ATR-FTIR）增加，而 CO/酰胺 I（ATR-FTIR）、PO/酰胺 I（ATR-FTIR）和%mineral（TG）比值降低。压缩延伸值随着暴露时间的延长而增加，牙本质类型之间存在显著差异（p<0.001，所有情况），牛牙本质的增加值更高。然而，弯曲强度（MPa）在组间无差异。我们还观察到组成变量（即 PO/酰胺 I、CI 和%mineral）与压缩延伸之间的相关性。
人牙和牛牙在微观结构、化学成分、力学强度以及对 pH 循环脱矿/再矿化过程的反应方面存在差异。
在体外研究中用人牙替代牛牙时，这些差异可能构成潜在的局限性。
