الفهرس 
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Abstract
Background: The passive fit is an important factor to reduce the loading on the implant/abutment and supporting bone structure and to maintain mechanical and biological equilibrium. Ill-fitting prostheses may create stresses which cause some complication on bone and implant. Aim of study: To compare stress transmission character on abutment of vertical misfit of bar framework of overdenture on implant abutment versus horizontal misfit on stress transmitted mandibular to bar retained overdenture. Materials and Methods: The in-vitro study was carried out on acrylic resin model representing mandibular completely edentulous ridge and silicone auto-polymerized soft liner material that covering residual ridge and retro molar area was prepared. Then the Hader bar was fabricated which connected one pair of dummy implants were inserted in canine regions in acrylic resin model. The four strain gauges were connected to each implant. Eighteen frame works with misfit were prepared. According to thickness and direction of misfit, the frame works were divided into two main groups. group A: nine frame works with different levels of vertical misfit (0.1, 0.2 and 0.3). group B: nine frame works with different levels of horizontal misfit (0.1, 0.2 and 0.3), after that, the overdentures were prepared. Finally, the load was applied by using universal testing machine. Data was collected and statistically analyzed. Result: By comparison between vertical misfit and horizontal misfit at 0.1, 0.2and 0.3at implant canine abutment was statistically significant different at 0.05 level of significant along mesiodistal direction and labiolingual direction for both side right and left Conclusion: Vertical misfit of bar framework on implants at canine region loading of 0.1mm thickness is favorable for dissipating stress than horizontal misfit at the same thickness and it is more favorable for dissipating stress than vertical and horizontal at 0.2 and 0.3mm thickness for both vertical and horizontal misfits.