Effect of shrinking and no shrinking dentine and enamel replacing materials in posterior restoration: A 3d-fea study

The aim of the present study was to investigate the effect of shrinking and no shrinking dental filling materials combination in posterior restorations under the combined effects of polymerization shrinkage and occlusal load by means of 3D Finite Elements Analysis. Six computer-generated and restored class I or class II cavities models of a lower molar were designed in the CAD software and evaluated according to the cavity and restorative procedure. Different shrinking and no shrinking adhesive materials combination with diverse Young’s modulus were considered. A food bolus was modeled on the occlusal surface replicating the chewing load using static linear analyses Polymerization shrinkage was simulated for the shrinking different restorative materials. The maximum principal stress was selected as analysis criteria. All models exhibited higher stresses along the dentine restoration interfaces with different magnitude and a similar stress trend along enamel restoration interface. Stress values up to 22 MPa and 19 MPa were recorded in the enamel and restoration, respectively. The use of elastic not shrinking material layer in combination with bulk fill composite reduced the stress magnitude in dentine and enamel to replace dental tissues. Class I and class II posterior cavities adhesively restored with shrinking filling material’s combination showed the most unfavorable stress concentrations and the multilayer technique is a promising restorative alternative in posterior adhesive restorations when deep dentin and enamel volumes are missing.