In this study a high resolution structural analysis revealed that enamel prisms are surrounded by an interface that is discontinuous with frequent mineral to mineral contact separated by gaps. This contact manifests either by crystallites bridging the boundary between prismatic and interprismatic enamel or continuous crystallites curving and bridging the interprismatic enamel to the prisms. The geometrical resolution of this TEM investigation of the interfaces is ≤2 nm as a basis for micromechanical models. Within this resolution, contrary to existing structural descriptions of dental enamel structure in materials science literature, here the crystallites themselves are shown to be either in direct contact with each other, sometimes even fusing together, or are separated by gaps. Image analysis revealed that on average only 57 ± 15% of the interface consists of points of no contact between crystallites. This work reveals structural features of dental enamel that contribute important understanding to both the architecture and mechanical properties of this biological material. A new structural model is proposed and the implications for the mechanical properties of dental enamel are discussed. STATEMENT OF SIGNIFICANCE: In this study a high resolution structural analysis, employing focused ion beam and transmission electron microscopy revealed that enamel prisms are surrounded by interfaces that are discontinuous with frequent mineral to mineral contact separated by gaps. Although the interfaces in enamel have been investigated previously, existing studies are lacking in detail considering the geometry and morphology of the interfaces. We think that this result is of great importance when it comes to the understanding of the mechanical properties. In our opinion the concept of soft sheaths is no longer feasible. The resulting observations are included in a new structural model which provides new qualitative insights into the mechanical behavior. Existing analytical models were applied to simulate the new geometrical structure.

中文翻译：

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牙釉质中界面的几何结构：FIB-STEM研究。

在这项研究中，高分辨率的结构分析表明，搪瓷棱镜周围是不连续的界面，频繁的矿物与矿物之间的接触被间隙隔开。这种接触可以通过微晶桥接在棱柱形和棱晶间的釉之间的边界来体现，也可以通过连续的微晶弯曲和桥接棱晶间的釉质到棱镜上来体现。该TEM研究界面的几何分辨率≤2 nm，作为微力学模型的基础。在此分辨率内，与材料科学文献中对牙釉质结构的现有结构描述相反，此处的微晶本身显示为彼此直接接触，有时甚至融合在一起，或被间隙隔开。图像分析表明，平均只有57±15％的界面由微晶之间没有接触的点组成。这项工作揭示了牙釉质的结构特征，这些特征对这种生物材料的结构和机械性能都有重要的了解。提出了一种新的结构模型，并讨论了其对牙釉质力学性能的影响。重大意义的陈述：在这项研究中，采用聚焦离子束和透射电子显微镜的高分辨率结构分析表明，搪瓷棱镜周围是不连续的界面，频繁的矿物与矿物接触被间隙隔开。尽管先前已经研究过搪瓷中的界面，考虑到界面的几何形状和形态，目前缺乏详细的研究。我们认为这一结果对于理解机械性能非常重要。我们认为，软护套的概念不再可行。所得的观察结果包含在新的结构模型中，该模型提供了对机械行为的新的定性见解。现有的分析模型被应用于模拟新的几何结构。