Effect of Aging on Plastic and Damage Mechanical Behavior of Dentin

: Transparency is a common pathology in aged teeth due to the dentin tubules are filled up with mineral crystals. The mechanical properties of dentin are also affected by ultrastructure changed in the aged dentin. Nanoindentation test is a popular technique to assess the elastic mechanical properties of dentin, while it’s difficult to obtain inelastic mechanical parameters since the indenter tip caused a complex stress distribution within dentin. The plastic-damage model incorporating finite element method is adopted to characterize the plastic and damage behaviors of dentin based on the nanoindentation experiments. The numerical simulations indicate that yield strength of dentin increased with aging. The capacity for energy dissipation via inelastic deformation which reflects the materials’ toughness decreases with increase of age. In addition, the numerical simulations also show that the magnitude of damage decreases with aging. The degradation of the unloading stiffness was caused by the damage at beneath the indenter.