Effects of cold-cured PMMA reinforcement by E-glass fibers impregnation

Abstract

OBJECTIVES: Cold-cured PMMA is a common material for fabrication of appliances such as orthodontic retainers. However, cold-cured PMMA has lower degree of polymerization than the heat-cured and this leads to inferior biomechanical properties and fracture vulnerability. Reinforcement of cold-cured PMMA using chopped and impregnated E-glass fibers was hypothesized to be a solution. METHODS: Specimens of cold-cured PMMA powder mixed with different concentrations of chopped E-glass fibers (0 - 5 wt.%) were prepared by using a new mixing method which does not need addition of extra monomer (MMA). After the specimens were stored at various conditions (room temperature and ambient humidity for 1 day and 7 days; water storage at 37oC for 7, 14 and 30 days), 3-point bending tests were performed to test the flexural strength and SEM images were taken to assess the fractured morphology and fibers embedment to the PMMA matrix. The data was analyzed by 1-way ANOVA and Tukey post hoc test. RESULTS: In general, all fiber-impregnated cold-cured PMMA showed a higher flexural strength than the control at various storage conditions, except for 1 wt.% fiber concentration. The reinforcing ability decreased with increase in the duration of water storage condition. SEM images showed a good impregnation of E-glass fibers to PMMA matrix. CONCLUSIONS: A new E-glass fiber impregnation method in cold-cured PMMA, which is immediately transferable and usable in dental clinics/laboratories, was successfully developed. Such method may increase of the cold-cured PMMA flexural strength.