urpose: The goal of this study was to compare and evaluate stress transmitted to overdenture abutment tooth supported by polyethylene ribbon bar reinforced composite resin of hybrid type, the hybrid type includes Nano-hybrid composite and Micro-hybrid composite
Methods: Edentulous educational acrylic model modified to receive two canine teeth and duplicated to ten models. Poly vinyl silicon impression material was packed to simulate mucosa covering the ridge. The canines prepared to receive metal jacket and then infibra ribbon bar constructed on the abutments, mandibular over denture constructed to each model over the bar, the ten models divided equally into two groups,
Group I: Five models received mandibular overdenture supported by two canines splinted with ribbon fiber bar reinforced with Nano-hybrid composite.
Group II: Five models received mandibular overdenture supported by two canines, splinted with ribbon fiber bar reinforced with Micro-hybrid composite.
Installation of strain gauges around each surface of the abutment, Universal testing machine used to apply load to each model Unilateral (50 N) and bilateral (100 N) vertical static load applied at 1st molar area to measure µ-strains at buccal, lingual, mesial and distal surfaces of the abutment. the outcomes collected and statistically analyzed to compare between the two groups.
Result: - Infibra ribbon bar reinforced by Nano-hybrid composite and infibra ribbon bar reinforced by Micro-hybrid composite exhibits No significant difference of micro strain transmitted to overdenture abutment except labial surface.
- Under bilateral loading, Infibra ribbon bar reinforced with Nano-hybrid composite bar transmit higher micro strain to all labial, lingual, and mesial surfaces of overdenture abutment than infibra ribbon bar reinforced with Micro-hybrid composite except distal surface.
Conclusion: -Infibra ribbon bar reinforced with hybrid type composite decrease stresses transmitted to mandibular over denture abutment
-Regarding stress distribution Micro-hybrid composite is the material of choice to construct infibra ribbon bar over Nano-hybrid composite.