Evaluation of stresses in maxillary first premolar restored with ceramic inlays and onlays by 3D finite element analysis: An in vitro study

Aim: The present study evaluated the effect of different cavity configurations on stresses generated in maxillary first premolars restored with ceramic inlays and onlays using a finite element analysis (FEA). Materials and Methods: An extracted maxillary first premolar was used to generate a 3D FEA model from which three FEA models were designed for inlay designated as Group A and two FEA models for onlay designated as Group B. Further, based on the cavity design, they were subdivided into A1—mesio-occlusal, A2—disto-occlusal cavity, A3—mesio-occlusal distal cavity, and B1—conventional onlay preparation, B2—conservative onlay preparation. Leucite and lithium disilicate ceramics were the materials tested. An axial load of 200 N was applied vertically on the Occlusal surface. A static FEA was performed to analyze the stresses generated. Outputs of minimal principal stresses (MPS-compressive) on enamel, maximum von Misses stress values in MPa in dentin, and restoration were recorded and tabulated. Results: MPS recorded in enamel were in the order GrA3 > GrA2 > Gr B1 > GrB2 >GrA1. The von Mises stresses generated in dentin were highest for GrA2 (65.4 MPa), followed by Groups A3, A1, B2, and B1 (24.5MPa). The ceramic materials evaluated did not significantly influence the stresses. Conclusion: None of the cavity designs or the materials tested resulted in deleterious stresses leading to failure. Inlays and onlays prove to be reinforcing restorations in maxillary first premolars, with onlays having an embracing effect on the remaining sound tooth structure.