Recent observations have shown that enamel exhibits creep behavior during indentation. In this paper, we develop a viscous creep model for enamel that considers the basic shape of the apatite crystallites and treats the thin protein layer between the crystallites as a viscous fluid. The approach enables identification of the main flow planes in the anisotropic enamel structure and the influence of the volume fraction of the apatite crystals. Nanoindentation data showing creep are interpreted consistently and viscosities attributed to the protein layer are evaluated.

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