Mechanical properties and ultrastructural characteristics of a glass fiber-reinforced composite

Purpose: To examine the ultrastructural characteristics of a fiber-reinforced composite (FRC) and its behavior in vitro as a framework for fixed partial dentures (FPDs). Methods: A total of 40 specimens were prepared using extracted teeth fixed in methacrylate blocks as supports for the FPD, then the specimens were divided into four groups depending on whether a retaining box was used to fix the FPD to the support teeth, and on whether a composite pontic was assembled on top of the fibers. Fracture testing was performed in a universal testing machine (1 mm/minute). Fracture strength values and failure types were statistically compared for each group. Results: Using retaining boxes did not improve the mechanical behavior of the restorative system. The weakest element of the system was the composite tooth constructed on top of the FRC.