Probing Heterogeneity in Bovine Enamel Composition through Nanoscale Chemical Imaging using Atom Probe Tomography

Olivia Licata, Upoma Guha, Jonathan D. Poplawsky, Nirupam Aich, Baishakhi Mazumder

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Objective: The aim of this study was to determine the heterogeneity in chemical composition of bovine enamel using atom probe tomography, and thereby evaluate the suitability of bovine enamel as a substitute for human enamel in in vitro dental research. Design: Enamel samples from extracted bovine incisor teeth were first sectioned using a diamond saw and then milled into needle-like samples (<100 nm diameter) by focused ion beam (FIB) coupled with a scanning electron microscope (SEM). These samples were analyzed in the atom probe to acquire three-dimensional (3D) images and quantify the atomic chemistry and distribution in bovine enamel. Results: For the first time, the atomic-level composition and clustering of major constituents and impurities within bovine enamel were determined and imaged. We discovered that the chemical composition of bovine enamel is spatially inhomogeneous at the atomic scale. The average bulk Ca/P ratio, ∼1.4, was in agreement with previously reported literature values from alternative conventional methods. When assessed locally at the atomic scale, the Ca/P ratio varied between 1.1 and 2.03. We also discovered that the Mg impurities were significantly segregated throughout the enamel, and such clustering influenced the variation of Ca/P ratios. The increase in Mg concentrations, near the Mg clusters, correlated with increased Ca and decreased P concentrations. Conclusion: The presented findings of variability in local composition should be taken into account when interpreting dental research results from bovine enamel.

Original languageEnglish
Article number104682
JournalArchives of Oral Biology
Volume112
DOIs
StatePublished - Apr 2020

Funding

The authors acknowledge the time provided for using atom probe tomography instrument as part of a user project at the Center for Nanophase Materials Sciences within the Oak Ridge National Laboratory, which is a Department of Energy (DOE) Office of Science User Facility. All authors gave their final approval and agree to be accountable for all aspects of the work. The authors declare ‘no conflicts of interests’.

Keywords

  • Caries
  • Dentin
  • Electron microscopy
  • Elemental distribution
  • Hydroxyapatite
  • Nanotechnology

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