چكيده به لاتين
Abstract
Acrylic bone cements are widely used in orthopedics and arthoplasty in order to fill the cavity between the implant and bone. However, lack of adequate biocompatibility of these cements with body tissues and extensive heat generated during the polymerization may lead to some complications for the patients. In this regard, incorporating some additive materials, such as hydroxyapatite, as an secondary phase into the bone cements has been recognized as an effective solution for this problem. Not only does the hydroxyapatite enhance the biocompatibility, but it also reduces the maximum curing temperature significantly. Mechanical properties of acrylic bone cement in its main application, that is transferring and distributing the in vivo loads from implants to bones, is of utmost importance. Researchers have proved that hydroxyapatite as a reinforcing phase is capable of improving some mechanical properties like compressive strength and modulus and hardness. Fracture toughness is another mechanical property which describes the resistance of a material to crack growth under static loading. Many researchers have investigated the effect of hydroxyapatite on mode I fracture toughness. Nevertheless, since in vivo stress state to which bones are subjected is a combination of tensile and shear (mixed mode) loading condition, considering merely tensile loading to study fracture resistance of PMMA/HA nano-composite seems to be inadequate.
The aim of this paper was to evaluate the effects of HA nano-particles on the mixed mode fracture toughness of acrylic bone cements. It was found that adding this bioceramic results in a decreases in the fracture toughness of bone cement in all fracture modes. Moreover, the experimental results were compared to the conventional MTS and generalized MTS criteria. This comparison showed that the generalized MTS criterion could provide better estimations for experimental results.
Keywords: Acrylic Bone Cement, Hydroxyapatite, Mixed Mode I/II Fracture Toughness, MTS and GMTS Fracture Criteria.
