The Poisson’s Ratio of enamel, dentin and dental restoration materials

Abstract

The Poisson ratio and the Young’s modulus form a pair of independent material constants of solids. For hard tooth tissues the Poisson’s ratio should correspond to the Poisson’s ratio of restorative materials in order to avoid overstresses at the border of the sections, restoration material-enamel and restoration material-dentin on microscopic level. In this paper on base orientation dependencies the extremal (minimum and maximum) Poisson’s coefficients of dentin and enamel are calculated. In the analysis, dentin and enamel was considered as an anisotropic medium with hexagonal symmetry with a known matrix of elastic constants. It is established that the interval of possible values of the Poisson’s ratio of dentin and enamel is much wider than the range of changes in the Poisson’s ratio of known dental composite materials, which in some cases can reduce the quality of restorations in microvolumes. It is shown that the maximum value of the Poisson’s ratio of dentin (0.534) is greater than the upper theoretic limit for the Poisson’s ratio of isotropic materials.