Biomechanical Evaluation of CAD/CAM Restorative Materials for Maxillary Second Premolar Crowns Using Three-Dimensional Finite Element Analysis

Background/Objectives: This study evaluated how the elastic modulus of CAD/CAM crown materials affects the stress distribution within a maxillary second premolar and its supporting structures. Methods: A maxillary premolar was digitally reconstructed for finite element analysis. Three crown materials with differing elastic moduli (210, 70, and 37.95 GPa) were modeled under a 300 N static vertical occlusal load, with maximum and minimum principal stresses as the primary outcome measures. Results: At standardized, mesh-verified probe locations, crown-body stress increased monotonically with material stiffness (zirconia > VITA Suprinity > VITA Enamic): outer axial wall stress was ~60% higher for zirconia (11.4 MPa) than for VITA Enamic (7.0 MPa). In the supporting tooth structures the ordering was reversed, the more compliant crown transferring more stress to the tooth at equivalent locations, with enamel probe stress ~29% and dentin probe stress ~52% higher for VITA Enamic than for zirconia. The crown margin was the only region in which tensile stress approached or exceeded the compressive magnitude, particularly for the stiffer materials. Conclusions: The elastic modulus of the restorative material significantly influenced the stress state within the crown (differences up to ~60% at equivalent locations), while its influence on the supporting tooth structures, although measurable at equivalent locations, was small in absolute terms (about 1 MPa in dentin and 3 MPa in enamel). This provides biomechanical context to guide clinical material selection.