[Photoelastic studies for the fixation of osteosynthesis plates]

Because of the biomechanics of the mandible, several viewpoints must be considered in stable metal plate osteosynthesis. A particular AO mandibular dynamic compression (DC) plate with perforations in a 45 degrees arrangement ("Freiburg Zuggurtungsplatte") has been developed to create an interfragmentary pressure zone in the region of the teeth during function. Photoelastic experiments showed that interfragmentary pressure developed due to this arrangement of perforations. To avoid a gap in the lingual region distant from the plate and to enable interfragmentary pressure in this region during function, converging screws are discussed. Photoelastic experiments showed that by slight inclination of the screws in convergent position the interfragmentary pressure is already increased in the lingual fracture gap distant from the plate. For a better guide of the screws in convergent position, an alteration of the spheric DC slide hole should be considered.