The purpose of this study was to estimate the fatigue life of premolars restoredwith two dental ceramics, lithium disilicate (LD) and polymer infiltrated ceramic (PIC) usingthe numerical method and compare it with the published in vitro data.Methods. A premolar restored with full-coverage crown was digitized. The volumetric shapeof tooth tissues and crowns were created in Mimics®. They were transferred to IA-FEMeshfor mesh generation and the model was analyzed with Abaqus. By combining the stressdistribution results with fatigue stress–life (S–N) approach, the lifetime of restored premolarswas predicted.Results. The predicted lifetime was 1,231,318 cycles for LD with fatigue load of 1400 N, whilethe one for PIC was 475,063 cycles with the load of 870 N. The peak value of maximumprincipal stress occurred at the contact area (LD: 172 MPa and PIC: 96 MPa) and central fossa(LD: 100 MPa and PIC: 64 MPa) for both ceramics which were the most seen failure areasin the experiment. In the adhesive layer, the maximum shear stress was observed at theshoulder area (LD: 53.6 MPa and PIC: 29 MPa).Significance. The fatigue life and failure modes of all-ceramic crown determined by thenumerical method seem to correlate well with the previous experimental study.

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