Effect of hydroxyapatite filler concentration on mechanical properties of poly (methyl methacrylate) denture base

Poly ( methyl methacrylate) or PMMA is an acrylic material has been used widely as a denture base material. The denture base is subjected to various stresses during the function, these include tensile and flexural stresses. The current study was aimed to experimentally evaluate the effect of different filler concentrations on physical and mechanical characteristics of PMMA/HA composite. PMMA reinforced with different ratios (i.e. 0, 5, 10, and 15 wt%) of silane treated HA were prepared to study the effect of HA concentration on the mechanical properties of acrylic denture base material. Tensile, flexural and fracture toughness tests were conducted to evaluate the mechanical performance. The fracture surfaces of all the composites were studied using scanning electron microscopy. The hardness of the composite was investigated using Vickers hardness. Independent t-test was also conducted to evaluate the significant difference in the values measured as a function of different filler loading. Data analyses showed a significant improvement (P < 0.05) in the tensile and flexural modulus of the composite 26% and 27.3% respectively, as a result of increasing the HA loading to 15 wt%. However, no significant difference (P > 0.05) was detected in the tensile and flexural strength as function of HA incorporation. A small increment of only 1.63% and 3% in the tensile and flexural strength respectively, was achieved at very low filler loading i.e. 5 wt%. An improvement of only 7.8% in the surface hardness was observed for PMMA loaded with 15 wt% of HA.