Hardness could found to be sensitive to the residual monomer content in the polymerized resins; the hardness is an effective method to evaluate the polymerization depth of resin materials. In addition, hardness had used to predict the wear resistance of dental materials. Materials and Methods: Acrylic resin specimens had divided into two groups according to the type of material tested (group I: conventional heat cured acrylic resin, group II: resin impregnated fiberglass reinforced complete

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... ure base). Vicker's micro hardness tester was used to measure Vicker's hardness number (VH) of the acrylic specimens in which diamond indenter was applied under 25 g load for 10 seconds time evaluated by 20 x objective lens. Results: The VH values of resin impregnated fiberglass reinforced acrylic resin showed statistically insignificant lower values (as P < 0.05) than conventional heat cured acrylic resin. Conclusion: Unreacted monomer would act as a plasticizer and weaken the matrix. Heat cured PMMA could perform better in this aspect that the residual monomer content was less when compared to PMMA reinforced through other mechanisms.