Fracture Micromechanism of the Hierarchically Organized Biocomposite (Dentin of the Human Teeth)

Abstract

Cracks in the thin samples of teenage dentin were examined on the nanoscale (TEM) and microscale (optical microscopy in the transmission light). Cracks in the bioorganic dentin matrix of the teenage dentin on the nanoscale behave like a crack in viscoelastic media, where the plastic zone develops ahead of a crack tip. There are pore-like satellite cracks in the narrow strip ahead of a microcrack tip. These satellite cracks have the tendency to merge with the main crack. The character of crack growth does not depend on the age of teenage dentin, while the angle at the crack tip is governed by the filler of the bioorganic dentin matrix. The presence of both collagen fibres and inorganic component in the dentin matrix does not change the type of its deformation behavior but plays the role of strengthening elements in a viscoelastic media. The mechanism of crack growth on the nanoscale is similar to the mechanism of microcrack development.