The origin of remarkable resilience of human tooth enamel

Abstract

<jats:p>The mechanical properties of human tooth enamel depend not only on test locations but also on the indentation depth. However, it remains uncertain what roles the depth-dependant properties play in mechanical performance of enamel. Here we reveal that a change in the mechanical properties of enamel, in particular its strength, with increasing indentation depth promotes inelastic deformation in material. In doing so, the severity and extent of stress concentration is reduced. Furthermore, we observed that following unloading, self-recovery occurs in enamel. These findings improve our understanding of the underlying mechanisms responsible for the remarkable resilience of enamel.</jats:p>