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Chemical gradients in human enamel crystallites

机译：人牙釉质微晶中的化学梯度

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摘要

Dental enamel is a principal component of teeth(1), and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades(2). Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society(3). Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success(4-6). This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients(7-9). Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca-5(PO4)(3)(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.Hydroxylapatite crystallites in human dental enamel show gradients in chemical composition, with a layer of magnesium enrichment on each side of a core rich in sodium, fluoride and carbonate ions.
机译：牙科搪瓷是牙齿（1）的主要成分，并进化以承受大量的咀嚼力，抵抗机械疲劳和承受数十年（2）的磨损。由发育缺陷或蛀牙（龋）引起的功能损伤和牙釉质丧失，影响健康和生活质量，与社会相关的成本（3）。虽然过去十年已经看到了我们对搪瓷形成（Amelogesesis）的理解和成熟牙釉质的功能性质的进展，但试图修复该材料中的病变或在体外合成它具有有限的成功（4-6）。这部分是由于牙釉质的高度分层结构以及由化学梯度产生的额外复杂性（7-9）。在这里，我们展示了使用原子级定量成像和相关光谱，即羟基磷灰石（Ca-5（PO4）（3）（3）（OH））的纳米级微晶，其是搪瓷基底构建块，包括两个富含纳米层侧翼含有富含钠，氟化物和碳酸盐离子的镁;这种三明治芯被壳体包围，壳体浓度较低的因子缺陷。基于密度函数理论计算的机械模型和X射线衍射数据预测，由于化学梯度，在酸性介质中的结晶核的优先溶解，因此由于化学梯度而产生的残余应力。此外，应力可能影响搪瓷的机械弹性。两个额外的层次层建议了在牙底生物发生过程中对晶体生长的生物控制的可能性新模型，并且在牙齿发育过程中对生物标志物的保护的提示。人牙釉质中的羟基磷灰石微晶显示化学成分中的梯度，具有一层镁富含含钠，氟化物和碳酸盐离子的核心的每一侧的富集。

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  • 来源
    《Nature》 |2020年第7814期|66-71|共6页
  • 作者

    DeRocher Karen A.; Smeets Paul J. M.; Goodge Berit H.; Zachman Michael J.; Balachandran Prasanna V.; Stegbauer Linus; Cohen Michael J.; Gordon Lyle M.; Rondinelli James M.; Kourkoutis Lena F.; Joester Derk;

  • 作者单位

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Cornell Univ Sch Appl & Engn Phys Ithaca NY 14853 USA|Cornell Univ Kavli Inst Cornell Nanoscale Sci Ithaca NY USA;

    Cornell Univ Sch Appl & Engn Phys Ithaca NY 14853 USA|Oak Ridge Natl Lab Ctr Nanophase Mat Sci Oak Ridge TN USA;

    Univ Virginia Dept Mat Sci & Engn Charlottesville VA USA|Univ Virginia Dept Mech & Aerosp Engn Charlottesville VA USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

    Cornell Univ Sch Appl & Engn Phys Ithaca NY 14853 USA|Cornell Univ Kavli Inst Cornell Nanoscale Sci Ithaca NY USA;

    Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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