Effects of alumina and hydroxyapatite nanoparticles on fracture toughness of PMMA based dental composite

Polymethylmethacrylate (PMMA) based dental and bone composites are used frequently in biomedical applications as implants، bone cements، restorative materials and etc. This is mainly because of some characteristics of PMMA such as biocompatibility، good mechanical properties and its low cost. However، in comparison with bone and dentin، PMMA based dentures or implants have lesser fracture toughness (i. e. smaller crack growth resistance) which makes them very susceptible to brittle and sudden failures. The use of nano additive materials like hydroxyapatite and alumina as filler particles may probably increase the crack growth resistance of such composites. Hence in this research the effects of adding different weight percentages of these two nano particles are examined on mode I fracture toughness of PMMA based denture composites. The experimental fracture toughness results demonstrated that the fracture resistances of manufactured nano-composites are increased in general relative to neat PMMA. The influence of alumina was more pronounced than the use of hydroxyapatite particle. The highest increase in fracture toughness was observed for composite containing 10% hydroxyapatite and 6% alumina.