Three-Dimensional Finite Element Analysis of Stress Distribution in Zirconia and Titanium Dental Implants
Zirconia has been presented as an alternative biomaterial to titanium, commercially presented as a single-body implant and/or as an abutment, demonstrating clinically biocompatible favorable results in white and rose esthetics. However, the number of long-term in vivo studies and mechanical tests evaluating the response of stress distribution compared with titanium implants is still limited. The aim of the study was to compare the principal peak stresses in the peri-implant bone around titanium and zirconia implants using the finite element method. Four groups of 3-dimensional models were constructed for the tests: G1, external hexagon titanium implant with a zirconia abutment; G2, zirconia implant with a zirconia abutment; G3, single-body titanium implant; and G4, single-body zirconia implant. Axial and oblique loads of 100 N at 45° were simulated in the prosthetic crown. The bone results showed that the peak stresses decreased by 12% in zirconia implants with 2 parts for axial load and 30% for the oblique load. In single-body implants, the peak stresses decreased 12% in the axial load and 34% in the oblique load when a zirconia implant was used compared with a titanium implant. Although the stress values in megapascals are similar, it can be concluded that the zirconia implants decrease the stress peaks at the peri-implant bone area around the implant platform when compared with titanium implants.
Figure 1. Three-dimensional model of external hexagon implant (a), customized abutment (b), and bolt screw (c). Figure 2. Three-dimensional model of the single-body implant. Figure 3. Digital reconstruction from computerized tomography scan without any editing (a). Dental element 35 was stored and subsequently sectioned in its cervical region to provide the shape and size of the final prosthetic crown (b).
Figure 4. Figure of final models; external hexagon implant (a) and single-body implant (b). A cut-away view shows medullary bone (pink), cortical bone (gray), implant (green), screw (brown), connector (blue), gutta percha (purple), zinc phosphate cement (orange), infrastructure (dark yellow), and ceramic (light yellow). Figure 5. Three enamel cylinders were distributed on the occlusal surface of the prosthetic crown (a–b) to simulate occlusion contacts. Figure 6. Vertical load parallel to the long axis (a), oblique loading of 45° to the long axis of the tooth (b). Figure 7. Resulting mesh of finite elements in external view (a) and internal view (b). The results of elements for the model with the HE implant was 1 007 028 nodes and 617 222 and 1 338 505 nodes and 869 393 for elements with the single-body models.
Figure 8. For both loads, the average percentage of stresses decreased for the zirconia implants. Figure 9. Results of average percentage values for axial load. Figure 10. Results of average percentage values for axial load.
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