Effect of aluminum oxide powder reinforcement on degree of conversion, monomer release and flexural strength of heat-cured acrylic resin

Objectives: Effect and correlation of aluminum oxide powder on degree of conversion, residual monomer and flexural properties of heat-cured acrylic resin specimens were studied. Materials and methods: Heat-cured acrylic resin and aluminum oxide powders were used. Specimens of specific dimensions from unreinforced and reinforced acrylic resins using stainless steel plates were prepared. Degree of conversion was determined using FTIR Spectrometer. Released monomer was measured using isocratic high-performance liquid chromatography. Flexural strength was tested using three point-bending test. Results: Aluminum oxide reinforcement showed increased degree of conversion than that of the unreinforced specimens. Released monomer from reinforced specimens was lower than that of unreinforced specimens. Deflection at fracture of reinforced specimens was lower than that of unreinforced specimens. Flexural strength was increased by addition of 2.5 % and 5% aluminum oxide. There was a positive correlation between degree of conversion and flexural strength. There was a negative correlation between degree of conversion and monomer release. Conclusions: Aluminum oxide powder increased degree of conversion and flexural strength but reduced monomer release and deflection at fracture. There was a positive correlation between degree of conversion and flexural strength. There was a negative correlation between degree of conversion and monomer release. Clinical relevance: Aluminum oxide powder could reinforce the week acrylic resin denture base materials. Degree of monomer conversion during processing of acrylic resin denture base materials is very critical in determination of monomer release and mechanical properties of acrylic resin in service.