Bhasin, Harpreet Kaur2025-09-102025-09-102025-07-292025-09-10http://hdl.handle.net/1993/39322The mechanical behaviour of crowns fabricated from Multilayered Zirconia for mandibular molars in bruxers using Finite Element Analysis (FEA). Purpose: To evaluate and compare the mechanical behaviour of crowns made from multilayered zirconia for mandibular molars using finite element analysis (FEA) with the elastic modulus derived from nanoindentation testing, and to compare it with the reference monolithic zirconia crowns. Material & Methods: Two rectangular samples of multilayer Zirconia, ZirCAD Prime and ZirCAD Prime Esthetic, each measuring 10 mm x 16 mm x 4 mm, were prepared and tested for Nanoindentation using a Hysitron Nanoindenter. Ten readings were taken for each layer of Enamel, Intermediate, and Dentine, and the average value of elastic modulus and hardness were calculated and used to test the Finite Element Analysis of the crowns under various loading conditions. A mandibular left first molar typodont tooth was prepared for a full-coverage Zirconia crown with two different occlusal reductions of 1 mm and 1.5 mm and a full-coverage Crown was designed using in-lab CAD software. 3D models of tooth preparation and full-coverage crowns were created and merged using HyperView Player 2022.3 software. The tooth-crown complex underwent a vertical loading and horizontal loading of 540N and 200N, respectively, in the central fossa, as well as the buccal cusps, and the Maximum principal Stresses were calculated in the Zirconia crowns. The material properties were assumed to be homogeneous, isotropic, and linearly elastic. Results: 1 mm crowns experienced higher tensile and maximum principal stresses than 1.5 mm crowns, regardless of material. Horizontal forces increased stresses across all crown types and thicknesses. All Zirconia types showed similar behavior under the same conditions. Maximum principal stresses in crowns ranged from 90.4 to 154.4 MPa, while in tooth structure, they ranged from 1.2 to 22.9 MPa. Conclusion: Increasing the thickness of the crown material reduces the stresses transmitted to both the crown and the tooth structure. More stresses were observed in the crown-tooth assembly under horizontal loading compared to axial/vertical forces. No differences in Maximum principal stresses were observed between the different Zirconia crown materials.engMaximum Principal StressFinite Element Analysis