Effect of Thickness of Various Restorative Materials and Hybrid Layer on Stress Distribution of Direct Cervical Restorations of Teeth Using a Three Dimensional Structural Finite Element Analysis

Challenging clinical conditions such as bonded restorations can be effectively simulated using finite element analysis and the nature of stress and deformation that leads to the failure of restoration can be analyzed. Glass ionomer cement (GIC) and composite resin (a combination-bilayered restoration with a hybrid layer in between) are widely used restorative materials for cervical cavities. The aim of the study is to evaluate the effect of thickness of GIC and composite resin on stress distribution on cervical restorations. A finite element model was constructed and imported to three-dimensional (3D) image analysis. The model was layered with enamel, dentin and cementum and the cavity of specific dimension was prepared. The cavity was restored with solid blocks of restorative materials of varying thickness. The force was applied on the cusp with fixed support at the cervical area of the tooth and the analysis was carried out in ANSYS Workbench Version 19.0 .Ovoid shaped cavity with 6 µm thick hybrid layer showed least stress value of 0.574 Mpa amongst all the groups. It is concluded that a thicker hybrid layer reduces the stress within the restoration and a thicker GIC with hybrid layer under composite resin is a better option for a bi-layered restoration in the cervical cavity.