Influence of Cross-Section Design and Vertical Misfit on Stress Distribution in Overdenture Retaining System:...

Area of Science:

• Biomaterials Science
• Mechanical Engineering
• Dental Prosthetics

Background:

• Dental overdentures rely on retaining bar systems for stability.
• Understanding stress distribution in these systems is crucial for longevity.
• Material properties and design geometry significantly influence mechanical performance.

Purpose of the Study:

• To assess stress on overdenture-retaining bar systems using 3-D finite element analysis.
• To investigate the impact of varying cross-sections (round, ovoid, Hader) and misfit levels (50-200 μm).
• To compare stress generation across different metallic alloys (Au type IV, Ag-Pd, Ti cp, Co-Cr).

Main Methods:

• Developed 3-D finite element models using SolidWorks.
• Simulated screw settlement using ANSYS mechanical simulation software.
• Analyzed stress distribution on bar components, screws, and periimplant bone tissue.

Main Results:

• Increased misfit levels correlated with higher stress on all system components.
• Hader bar designs exhibited the highest stress values (bar: 730.71 MPa, screw: 59.66 MPa, bone: 42.96 MPa).
• Round bars fabricated from Type IV gold alloy demonstrated the lowest stress (bar: 193.99 MPa, screw: 10.27 MPa).

Conclusions:

• Vertical misfit significantly elevates stress within the overdenture-retaining bar system.
• Complex cross-sectional designs amplify stress on the bar, screw, and surrounding bone.
• Stiffer metallic alloys result in higher stress generation under all tested conditions.