The effect of glass flakes reinforcement on the surface hardness and surface roughness of heat-cured poly (methyl methacrylate) denture base material

Abstract

Background: Heat-cured poly (methyl methacrylate) the principal material for the fabrication of denture base havea relatively poor mechanical properties. The aim of this study was to investigate the effect of glass flakes used asreinforcement on the surface hardness and surface roughness of the heat-processed acrylic resin material.Material and method: Glass flakes (product code: GF002) pretreated with silane coupling agent were added toTriplex® denture base powder using different concentrations. A total of 100 specimens of similar dimensions (65 x 10 x2.5) mm were prepared, subdivided into 2 main groups of 50 specimens for each of the study tests. Ten specimens forthe control group and 40 specimens for each of the experimental groups (2%, 3%, 5%, and 7%) glass flakes content.The surface hardness was evaluated using the Shore D hardness test, while the surface roughness was evaluatedusing a profilometer device that detect the geometry of the specimen unpolished surface. Results were analyzedusing the Wilcoxon rank sum test and the 1-way analysis of variance, (P-value< 0.05).Results: The surface hardness tended to increase significantly p 0.05 with the increasing flakes concentration, as anincrease of 5.12% was recorded in surface hardness for the highest loading level; while the roughness showed asignificant increase that remained within the tolerable range –less than 2μm– (significant bacterial colonization wouldoccur if the surface roughness is more than 2μm).Conclusion: The addition of glass flakes to heat-cured poly(methyl methacrylate) enhanced the hardness of thematerial, the improvement was statistically significant for the higher glass flakes concentrations (5% and7%), while forthe surface roughness there were a constant increase in roughness along with the increasing glass flakes content