Effect of dentin tubules on the mechanical properties of dentin. Part I: Stress-strain relations and strength criterion

As known, there is a large number of dentin tubules in dentin. These tubule s have varying radii and are shaped into radially parallel pattern. The ani sotropy of microstructure of dentin shows that dentin should be treated as a material of varying transverse isotropy. In this Part, the elastic stress -strain relations and the quadratic strength criterion are established in t he form of having varying transverse isotropy, in the framework of micromec hanics to take into account of the effect of the microstructures-dentin tub ules. Simplified forms for isotropic and homogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also giv en. These theoretical models are very well supported by the experiments sho wn later in the continued paper (Part II).