FEA study for the mechanical strength evaluation of self-adhesive cements used for the restoration of integral ceramic inlays

Aim. The purpose of this study is to evaluate the strength of the adhesion of ceramic inlays (IPS max Press-Ivoclar) in 3 different clinical situations, while comparing the clinical performance of two different luting materials (Variolink Esthetic DC - Ivoclar and Maxcem Elite – Kerr). Materials and methods. The image processing was done using the Mimics 10 software. The purpose of the processing was to transform the 2D image collection into a volume representing the structure of a molar. After the reconstruction, using the SolidWorks 2013 CAD modelling program, geometric operations were performed to obtain three types of inlays. Three directions of stress have been chosen and they have been preserved for all 3 situations: the direction (Δ1) simulates a normal traction on the inlay, the direction (Δ3) simulates a shear stress, and the direction (Δ2) a combined oblique stress. The load forces modules were 90 and 230 N. Finite element analysis was performed with FEA Ansys 13 software. Results. Both types of luting cements have higher resistance values than the values recorded at both the surface and the interface. This indicates that either of the two application rates applied in any of the three directions will not damage any of the two types of luting materials. Due to the occurrence of shear stresses, in the case of iC inlay, the horizontal stress exceeds the value of the mechanical strength of cement for the accidental stress of 230 N, but neither in this case there will be no damage. Conclusion. Variolink II has better adhesion properties than Maxcem cement, which is why, regardless of the geometric configuration, the direction of the application force and the modulus used in the simulation, the adhesion of Variolink has higher mechanical strength.