Aberration-Corrected Transmission Electron Microscopic Study of the Central Dark Line Defect in Human Tooth Enamel Crystals

Reyes‐Gasga, J.; Hemmerlé, Joseph; Brès, E.

doi:10.1017/s1431927616011648

Cited by 14 publications

(6 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…2b shows an enamel grain with a CDL located in roughly the center. Fast Fourier transformation (FFT) analysis of the white square confirms that the viewing direction is along the [0001] zone axis and the CDL lies along (11 ̅ 00) planes, consistent with recent STEM observations [30]. The bright-field image of a carious lesion (Fig.…”

Section: Hrtem Imaging Of Demineralized Enamel Crystallitessupporting

confidence: 86%

Nanoscale pathways for human tooth decay – Central planar defect, organic-rich precipitate and high-angle grain boundary

et al. 2020

View full text Add to dashboard Cite

Section: Hrtem Imaging Of Demineralized Enamel Crystallitessupporting

confidence: 86%

Nanoscale pathways for human tooth decay – Central planar defect, organic-rich precipitate and high-angle grain boundary

et al. 2020

View full text Add to dashboard Cite

“…At the central region of the human tooth enamel crystals, a defect named as "the central dark line" (CDL) was observed. In transmission electron microscopy (TEM) images, the CDL showed a contrast similar to the "Fresnel contrast" of edge-on defects; that is, it appeared as a dark line with a width of ~1 nm out-of-focus in both cross-sectional and transverse section samples, but it was white in over-focus and disappeared in-focus (the Gaussian focus) [3][4][5]. Figure 1 Because enamel crystals begin to dissolve from the center during acidic attacks such as caries [6], the CDL is of particular interest.…”

Section: The Central Dark Linementioning

confidence: 99%

High Resolution STEM Images of the Human Tooth Enamel Crystals

Reyes‐Gasga

Brès

2021

Applied Sciences

Self Cite

View full text Add to dashboard Cite

High-resolution scanning transmission electron microscopy (STEM) images of human tooth enamel crystals, mainly in the high-angle annular dark-field (STEM-HAADF) mode, are presented in this work along the [1000], [10-11]. and [1-210] directions. These images allow knowing some structural details at the nanometric level of the human tooth enamel crystals and of the central dark line (CDL) observed at their centers. The transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images of the CDL showed the Fresnel contrast. In the STEM bright-field (STEM-BF) and annular-dark-field (STEM-ADF) images, the CDL was observed as an unstrain hydroxyapatite (HAP)-like zone but surrounded by a strained zone. In the STEM-HAADF images, the CDL appeared with a weak contrast, and its contrasts’ thickness was registered between 3 and 8 Å. The arrangement obtained in the STEM-HAADF images by identifying the bright points with the Ca atoms produced the superposition of the HAP atomic sites, mainly along the [0001] direction. The findings provide further information on the structure details at the center of enamel crystals, which favors the anisotropic carious dissolution at the CDL.

show abstract

“…Additionally, these lines cannot correspond to the well-known central dark line (CDL) in each enamel HAP nanocrystal . This is because, under the annular dark field detectors used to obtain better CDL detection than regular high resolution TEM, CDLs visually appear as brighter lines due to the higher z-contrast. − Our micrographs are acquired in the same way; hence, the dark lines we observed are not CDLs. These intracrystal nanocracks sometimes completely disappear before reappearing further along the same path and thus appear as dashed lines.…”

Section: Resultsmentioning

confidence: 99%

Role of the Mineral in the Self-Healing of Cracks in Human Enamel

et al. 2022

View full text Add to dashboard Cite

Human enamel is an incredibly resilient biological material, withstanding repeated daily stresses for decades. The mechanisms behind this resilience remain an open question, with recent studies demonstrating a crackdeflection mechanism contributing to enamel toughness and other studies detailing the roles of the organic matrix and remineralization. Here, we focus on the mineral and hypothesize that self-healing of cracks in enamel nanocrystals may be an additional mechanism acting to prevent catastrophic failure. To test this hypothesis, we used a molecular dynamics (MD) approach to compare the fracture behavior of hydroxyapatite (HAP) and calcite, the main minerals in human enamel and sea urchin teeth, respectively. We find that cracks heal under pressures typical of mastication by fusion of crystals in HAP but not in calcite, which is consistent with the resilience of HAP enamel that calcite teeth lack. Scanning transmission electron microscopy (STEM) images of structurally intact ("sound") human enamel show dashed-line nanocracks that resemble and therefore might be the cracks healed by fusion of crystals produced in silico. The fast, self-healing mechanism shown here is common in soft materials and ceramics but has not been observed in single crystalline materials at room temperature. The crack self-healing in sound enamel nanocrystals, therefore, is unique in the human body and unique in materials science, with potential applications in designing bioinspired materials.

show abstract

Aberration-Corrected Transmission Electron Microscopic Study of the Central Dark Line Defect in Human Tooth Enamel Crystals

Cited by 14 publications

References 39 publications

Nanoscale pathways for human tooth decay – Central planar defect, organic-rich precipitate and high-angle grain boundary

Nanoscale pathways for human tooth decay – Central planar defect, organic-rich precipitate and high-angle grain boundary

High Resolution STEM Images of the Human Tooth Enamel Crystals

Role of the Mineral in the Self-Healing of Cracks in Human Enamel

Contact Info

Product

Resources

About