Elsevier

Acta Biomaterialia

Volume 120, 15 January 2021, Pages 124-134
Acta Biomaterialia

Crystal misorientation correlates with hardness in tooth enamels

https://doi.org/10.1016/j.actbio.2020.07.037Get rights and content
Under a Creative Commons license
open access

Abstract

The multi-scale hierarchical structure of tooth enamel enables it to withstand a lifetime of damage without catastrophic failure. While many previous studies have investigated structure-function relationships in enamel, the effects of crystal misorientation on mechanical performance have not been assessed. To address this issue, in the present study, we review previously published polarization-dependent imaging contrast (PIC) maps of mouse and human enamel, and parrotfish enameloid, in which crystal orientations were measured and displayed in every 60-nm-pixel. By combining those previous results with the PIC maps of sheep enamel presented here we discovered that, in all enamel(oid)s, adjacent crystals are slightly misoriented, with misorientation angles in the 0°-30° range, and mean 2°-8°. Within this limited range, misorientation is positively correlated with literature hardness values, demonstrating an important structure-property relation, not previously identified. At greater misorientation angles 8°30°, this correlation is expected to reverse direction, but data from different non-enamel systems, with more diverse crystal misorientations, are required to determine if and where this occurs.

Statement of Significance

We identify a structure-function relationship in tooth enamels from different species: crystal misorientation correlates with hardness, contributing to the remarkable mechanical properties of enamel in diverse animals.

Keywords

Enamel
Misorientation
PIC maps
Hardness

Cited by (0)

Part of the Special Issue on Biomineralization: From Cells to Biomaterials, associated with the BIOMIN XV: 15th International Symposium on Biomineralization, held at the Ludwig Maximilian University, Sept 9–13, 2019, organized by Wolfgang Schmahl and Erika Griesshaber.

1

Previously publishing as Gelsomina De Stasio.