[Photoelastic comparison of the performance of varying fiber-reinforced framework designs in three-unit fixed partial...

Although there have been several reports about fiber-reinforced composite (FRC) fixed partial denture designs, different framework designs have not been sufficiently assessed. This study analyzed the differences between varying framework designs using FRC materials by two-dimensional photoelastic observation. Seven study models with a three-unit fixed partial denture replacing the first molar were fabricated. One without FRC was used as a control, and the other six were divided in two groups: one with the framework partially covering abutments, and the other with the framework completely covering abutments. For each group, the middle part of the framework was made with three different designs: straight bar, curved bar and curved-thickened bar. A vertical force of 400 N was applied to the occlusal center of each model. The resultant stress was observed photoelastically and recorded photographically. We found that the FRC framework provided strength support to the overall structure, and that the framework completely covering abutments with the curved-thickened bar showed the lowest stress level.