2015/02/12 by Lyle M. Gordon, Michael J. Cohen, Keith W. MacRenaris +3 · 2 citations
Earth and Planetary Sciences · Engineering · #nanoparticles nucleation surface interactions #Ion-surface interactions and analysis #Advanced Materials Characterization Techniques
paper · doi:10.1126/science.1258950
openalex publication_date 2015/02/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
Dental enamel, a hierarchical material composed primarily of hydroxylapatite nanowires, is susceptible to degradation by plaque biofilm-derived acids. The solubility of enamel strongly depends on the presence of Mg(2+), F(-), and CO3(2-). However, determining the distribution of these minor ions is challenging. We show—using atom probe tomography, x-ray absorption spectroscopy, and correlative techniques—that in unpigmented rodent enamel, Mg(2+) is predominantly present at grain boundaries as an intergranular phase of Mg-substituted amorphous calcium phosphate (Mg-ACP). In the pigmented enamel, a mixture of ferrihydrite and amorphous iron-calcium phosphate replaces the more soluble Mg-ACP, rendering it both harder and more resistant to acid attack. These results demonstrate the presence of enduring amorphous phases with a dramatic influence on the physical and chemical properties of the mature mineralized tissue.