The Effect of Polymerization Methods and Fiber Types on the Mechanical Behavior of Fiber-Reinforced Resin-Based Composites.

Purpose: Glass fibers were introduced to increase the fracture resistance of resin-based composites restorations; however, the poor polymerization between fibers and resin-based composite were sometimes noted and can cause debonding and failure. The purpose of this study was to investigate the effects of different polymerization methods as well as fiber types on the mechanical behavior of fiber-reinforced resin-based composites.

Materials And Methods: Seventy-five specimens were fabricated and divided into one control group and four experimental groups (n = 15), according to the type of glass fiber (strip or mesh) and polymerization methods (one- or two-step). A 0.2-mm-thick fiber layer was fabricated with different polymerization methods, on top of which a 1.8 mm resin-based composite layer was added to make a bar-shape specimen, followed by a final polymerization. Specimens were tested for flexural strength and flexural modulus. The failure modes of specimens were observed by scanning electron microscopy.

Results: The fiber types showed significant effect on the flexural strength of test specimens (F = 469.48, p < 0.05), but the polymerization methods had no significant effect (F = 0.05, p = 0.82). The interaction between these two variables was not significant (F = 1.73, p = 0.19). In addition, both fiber type (F = 9.71, p < 0.05) and polymerization method (F = 12.17, p < 0.05) affected the flexural modulus of test specimens; however, the interaction between these two variables was not significant (F = 0.40, p = 0.53).

Conclusions: The strip fibers showed better mechanical behavior than mesh fibers and were suggested for resin-based composites restorations reinforcement; however, different polymerization methods did not have a significant effect on the strength and failure mode of fiber-reinforced resin-based composites.