Zirconia Versus BioHPP Frameworks On Stresses Induced In Implants Supporting Structures Using ALL-ON-4® Protocol (Strain Gauge Analysis)

Objectives: This study was carried out to compare Zirconia & BioHPP frameworks regarding stresses induced on implants supporting structures with ALL-ON-4®protocol using strain gauge analysis.
Materials and Methods: Completely edentulous maxillary cast was prototyped using 3D printing technology. This was done via scanning an educational model and designing a STL file including all the details required; implants beds, mucosal space for mucosa simulation and vertical slots for strain gauges which were 1mm distal and labial to each implant. Printing was ordered and mucosa simulation was done. Four dummy implants were placed in their beds. Multiunit abutments were secured to the implants, then fixed detachable prostheses were fabricated. In this study two models were conducted: Model (1): Complete implant supported Zirconia fixed detachable prosthesis. Model (2): Complete implant supported BioHPP (Bio-High Performance Polyether) fixed detachable prosthesis. Strain gauges were supplied with fully encapsulated grids and attached wires. The wire used for strain gauges were insulated by a packing material. Micro strains were recorded at each site of the strain gauges with enough time elapsed between each testing.
The applied load started from zero up to 100N.
Results: The results obtained from this study revealed significant difference (P ≤0.05) between the Zirconia and BioHPP fixed detachable prosthesis on the average stresses falling on the implants when vertical bilateral load was applied. It also revealed that there was a statistically significant difference between the two-fixed detachable prosthesis when unilateral (vertical& oblique) load was applied as it was found that the BioHPP transmitted less stresses than Zirconia.
Conclusion: Within the limitations of this study, it could be concluded that, Unilateral loading was more traumatic to the implants compared to bilateral loading regarding the fixed detachable prosthetic materials as bilateral loading provides wide distribution of stresses. Also, unilateral loading was more traumatic to the implants in the Zirconia than BioHPP fixed detachable prosthesis. Finally, Zirconia can be considered the last choice dental materials especially those used in implant over structure owing to high stresses it transmits to the implants and supporting structures although of its superior esthetics and durability.