Effect of Glass-Fiber Reinforcement on the Flexural Strength of a Provisional Crown Material

This study aimed to evaluate the effect of different glass-fiber reinforcement ratios on the flexural strength of an autopolymerizing PMMA provisional restoration material and to determine the influence of thermal aging on these mechanical properties. PMMA specimens reinforced with glass fibers at 0.75%, 1.5%, 3%, 6%, and 12% by weight were prepared, along with a non-reinforced control group. Each group was divided into thermocycled and non-thermocycled subgroups (n = 10). A total of 120 specimens were tested. Flexural strength was measured using a three-point bending test after applying 2,500 thermal cycles (5 °C – 55 °C) to relevant subgroups. Before thermal cycling, only the 12% glass-fiber group demonstrated a significant increase in flexural strength compared with the control. After thermal cycling, the 12% group showed significantly higher flexural strength than all other reinforced groups and displayed results comparable to the control group. Thermal aging generally reduced flexural strength, except in the highest fiber-reinforced specimens. Glass-fiber reinforcement - particularly at 12% - enhances the flexural strength of autopolymerizing PMMA, providing improved performance after aging. Higher reinforcement ratios may offer clinical benefits for long-term provisional restorations.