PHOTOELASTIC ANALYSIS OF MINIPLATE OSTEOSYNTHESIS FOR MANDIBULAR ANGLE FRACTURES

Objective. The purpose of this study was to reassess Champy's findings , which were instrumental in justifying the theory of tension band pla ting for mandibular angle fractures. Study design. Ten anatomically co rrect mandibles were fabricated with a photoelastic resin. In five man dibles, angle fractures were created and fixated with a superior borde r miniplate; five uncut mandibles served as controls. Each mandible wa s loaded in a manner that simulated physiologic conditions. The intern al stress patterns were preserved within the models by completing a st ress freezing cycle. Results. The stress patterns in the experimental mandibles virtually replicated the patterns seen in the controls. Stre ss fringes were present surrounding the outer screws, indicating that these screws were subjected to pull-out forces. Conclusions. There is greater force on the outer screws that may contribute to fixation fail ure. The theory of tension band plating for mandibular angle fractures is accurate but Champy's model is oversimplified.