Effect of 180-week water storage on the flexural properties of E-glass andsilica fiber acrylic resin composite

Purpose: The aim of this study was to determine the effect of long-term wat er immersion on the flexural properties of fiber-reinforced composite. Mate rials and Methods: Continuous, woven, silanized E-glass fibers and woven si lica fibers were used to reinforce heat-cured and autopolymerized denture b ase polymers. Fibers were oriented at a 45-degree angle to the long axis of the test specimens. Control specimens were unreinforced. Dry test specimen s and those stored in water for up to 180 weeks were tested with a 3-point loading apparatus. Results: Ultimate transverse strength and flexural modul us of unreinforced and fiber-reinforced composite test specimens decreased during water storage (P < 0.001, analysis of variance). Post hoc analysis r evealed that after the storage of 4 weeks no statistically significant redu ction occurred. Conclusion: The results of this study suggest that the ulti mate transverse strength of the fiber-reinforced composite made from E-glas s fibers is reduced by approximately 27% compared to the dry fiber-reinforc ed composite. The majority of the reduction occurred during 4 weeks of stor age in water and remained approximately at that level for 180 weeks.