Year: 2022
Type: article
Abstract: 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 crack-deflection 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.
Source: ACS Nano
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, U.S. Department of Health and Human Services, University of Pittsburgh, National Energy Research Scientific Computing Center, National Institutes of Health, Office of Science, Multidisciplinary University Research Initiative, Office of Naval Research, National Institute of Biomedical Imaging and Bioengineering, National Institute of Dental and Craniofacial Research, Division of Materials Research, Division of Graduate Education, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Air Force Office of Scientific Research, Lawrence Berkeley National Laboratory
Awards: G1102702650, G1380171086, G1523888516, G222768804, MAPPING OF TEMPORAL AND SPATIAL PHASE TRANSITIONS OF CACO3 IN ECHINODERM SKELETONS: KEY INSIGHTS INTO BASIC MECHANISMS IN BIOMINERALIZATION, G2713250197, Function of Keratin 75 in enamel, G3030284719, G3040920244, G3488658013, Graduate Research Fellowship Program, Cross-scale interactions between mineral and collagen for tendon-bone attachment, G3770966485, G4044739261, G4078792090, MAPPING OF TEMPORAL AND SPATIAL PHASE TRANSITIONS OF CAC03 IN ECHINODERM SKELETONS: KEY INSIGHTS..., G4917416065, G4994782167, G5226628132, Models to Predict Protein Biomaterial Performance, MAPPING OF TEMPORAL AND SPATIAL PHASE TRANSITIONS OF CACO3 IN ECHINODERM SKELETONS: KEY INSIGHTS INTO BASIC MECHANISMS IN BIOMINERALIZATION, G5590208929, G5648016710, G5662436926, G5721077460, G5912748570, G6098521345, G6191928423, G6216008487, G7050178259, G7057920781, G7142813775, G8138261068, Discovery of New Phenomena in Biomineral Formation, G9000175394, G96172096
OpenAlex ID: W4283377679