The effect of fiber reinforcement on the dimensional changes of poly methyl methacrylate resin after processing and after immersion in water: an in vitro study.

AIMS AND OBJECTIVES To evaluate and compare the effect of fiber reinforcement on the dimensional changes of heat-cured poly (methyl methacrylate) resin after processing and immersion in water. MATERIALS AND METHODS Three different heat-cure resins were selected for the present study: (1) Nonreinforced heat-cure methyl methacrylate resin, (2) High Impact heat-cured methyl methacrylate resin and (3) Fiberglass reinforced methyl methacrylate resin. Ninety samples were prepared using three different resins and denture bases obtained for the same. The amount of space between the tissue surface and the cast in the anterior, middle and posterior regions is measured after processing and immersion in water for 17 days using a traveling microscope having a least count of 0.001 cm. RESULTS Mean and standard deviation were calculated for the dimensional changes and were subjected to statistical analysis (Student t-test, unpaired). Among the three groups of resins, fiber reinforced heat-cured methyl methacrylate resin was found to be statistically highly significant in terms of dimensional changes when compared with the nonreinforced and high impact heat-cured resins. CONCLUSION Dimensional changes were evident in all the planes in the three groups studied and were in the following decreasing order-fiberglass reinforced heat-cured poly (methyl methacrylate) resin, high impact heat-cured poly (methyl methacrylate) resin and nonreinforced heat-cured poly (methyl methacrylate) resin. CLINICAL SIGNIFICANCE The fibers are added in order to increase the strength of acrylic resin. Considering only the strength may in turn affect the dimensional accuracy of the acrylic resin resulting in loss of retention and stability, affecting the fit of the denture.