Influence of the First Maxillary Molar Abutment Inclination on Stress Distribution Among Two Types of Zirconia Crowns: 3D Finite Element Analysis Study
ABSTRACT
Background:
Variations in the abutment inclination and occlusal force behavior may result in significant alterations in the mechanical features of dental crowns. Most previous studies consider a crown design, materials properties, heavy occlusal load, etc. However, the effects of abutment inclination and occlusion condition are important concerns in clinical practice and are still controversial.
Objective:
The main purpose of this thesis is to examine the resistance of prosthodontic zirconia-based crowns to masticatory stress resulting from different occlusion positions (centric occlusion, palatal and buccal crossbite malocclusion) in all force directions (vertical, oblique, and horizontal) using finite element analysis method.
Methods:
By utilizing engineering simulation systems, the von Mises stress, principal stress, shear stress, principal strain, and total deformation within the zirconia-based crown and surrounding structures are all considered in the simulations. Three-dimensional models (two groups (n=3/group)) involved the abutment teeth with their supporting structures, and two types of zirconia crowns, which were created (via MIMIC and Solidworks software) and analyzed (by ANSYS software). The mechanical characteristics of the elements employed in this examination were obtained from previously published literature.
Results:
Similar maximum stress responses were observed for both types of zirconia, although both types performed well in all loading conditions, while the abutment represented different inclined positions. Overall, the results provided a useful insight into the normal (centric) occlusion position and monolithic zirconia type for better load transfer efficiency and marginal integrity.
Conclusion:
The virtual models used in this thesis had all the characteristics of the prosthetic system under different masticatory loads. Clinicians should find a better centric occlusal balance to get even stress/strain distribution over the prosthetic component and surrounding structures to ensure long-term therapeutic outcomes for patients.
