Analysis of the Mechanical Behaviour of Biocompatible Dental Cements

Abstract

The classical elasticity theory assumes as basic hypothesis that materials have similar elastic properties in tension and compression. However, studies indicate that a wide range of materials such as cements, ceramics, graphite, composites and even some biological structures like bone, behave differently under tension and compression, i.e., in the elastic regime have diff erent Young’s modulus in tension and compression. These materials are known as bimodular materials. A correct approach to the simulation of mechanical behavior of these materials should consider these different properties. This work aims to simulate computationally the mechanical behavior of cementitious materials used in dental treatments, which require for their correct modeling, an accurate characterization of their properties. The mechanical properties of these materials were obtained from experiments performed by a dentist through uniaxial tension tests, uniaxial compression tests and three-point bending test. Resin cement selected for study was the Cement Post (Angelus ® - Lot No. 6425). Using the finite element method a reverse analysis was carried out in order to generate computer models that reproduce the experimental mechanical tests. The results obtained in the numerical analysis were compared with the results obtained in laboratory tests for samples of this dental cement, in order to determine the correct Young’s modulus in tension and compression and the rupture tension. In bending tests the relevant international standards applicable to dental materials do not consider, for calculating the flexural strength, the bimodular behavior of these material. It is concluded that in simulations of bimodular materials is required for greater accuracy more attention in the choice of their mechanical properties, mainly in finite element analysis. In the case of bending simulations, the correct kno wledge of the diff erent material Young’s modulus on tension and compression is relevant for having a consistent approach in order to determine the flexural strength and tensile strength of bent samples.