Deformation behavior of human dentin in liquid nitrogen: A diametral compression test

• Deformation behavior of human dentin under diametral compression is studied.
• Deformation of dentin is realized due to elasticity and plasticity at 300 K.
• Dentin behaves like a brittle solid at 77 K.
• Collagen fibers play a key role in the mechanism of crack termination in dentin.

Contribution of the collagen fibers into the plasticity of human dentin is considered. Mechanical testing of dentin at low temperature allows excluding the plastic response of its organic matrix. Therefore, deformation and fracture behavior of the dentin samples under diametral compression at room temperature and liquid nitrogen temperature are compared. At 77 K dentin behaves like almost brittle material: it is deformed exclusively in the elastic regime and it fails due to growth of the sole crack. On the contrary, dentin demonstrates the ductile response at 300 K. There are both elastic and plastic contributions in the deformation of dentin samples. Multiple cracking and crack tip blunting precede the failure of samples. Organic phase plays an important role in fracture of dentin: plasticity of the collagen fibers could inhibit the crack growth.

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