Ahmed Yahia Mohamed, Ahmed G. Ahmed And Emad Mohamed T. Agamy,

ABSTRACT
Objective: The Aim Of This Study Is To Compare The Influence Of Two Different Bar Materials On The Stress Distribution In Two Mandibular Implant Supported Overdentures, One Retained By A Titanium Bar And The Other Retained By A Zirconium Bar Attachment With Standard Bar Dimensions And Cross Section, Using Finite Element Analysis (FEA).

Materials and Methods: A Digital 3D Model Simulating A Mandibular Edentulous Situation Was Constructed, The Surface Of The Model Was Modified To Simulate The Mucosa And An Overdenture Supported By Two Implants Placed In Canine Area And Retained By A Bar Attachment, Two Models Were Created By Duplication, The Only Difference Was The Material From Which Bar Was Fabricated (cobalt Chromium And Zirconium), Two Types Of Loads Were Applied To The Model: Total Of 150 N Vertical And 45 Degree Oblique Loads On The Right First Premolar, Second Premolar And First Molar. The Stress Distribution Around Peri-implant Bone, Implant, Mucosa And Overdentures Was Recorded.

Results: The Maximum Recorded Stresses Under Vertical Loading Were 388.146 Mpa While Under Oblique Loading Were 247.667 Mpa. No Failure Occurred In Any Part Of The Model. All Maximum Stresses Were Less Than The Yield Strength And Within The Biological Range. Conclusion And Clinical Significance: Within The Limitations Of The Current Study, It May Be Conducted That The Use Of Zirconium Bar Exhibited Better Stress Distribution Than Co-Cr Bar.