Modeling the rheological properties of four commercially available composite core build-up materials

The aim of this study is to analyze viscoelastic properties of direct composite core (Lightcore, Build-it, Clearfil Photo Core, Rebilda). Experiments are preformed and mathematical models developed, based on derivatives of fractional order, to describe the viscoelastic properties of the studied materials. The basic assumption that materials are of memory type was proved to be correct. For each material, four fractional derivative models are used to fit experimental data and then one model, with smallest error between measured and calculated data for storage and loss modulus, is chosen. On the basis of mathematical model formulated here, it is possible to predict some viscoelastic properties of the materials that are important in clinical application. Central conclusion is that the four studied materials have different rheological properties although they are indicated for the same clinical procedure.