Modification of zirconia with hydroxyapatite for bioactive enhancement as dental implants

Abstract Zirconia is one of the best materials for making the crown in dental implant due to its excellent acid and base resistances and appearance close to natural teeth. In addition, its extraordinary mechanical properties render zirconia to be a potential candidate as dental implant, if its biocompatibility can be improved to promote adhesion to natural tissues. This study is to enhance the bioactivity of zirconia with the aim to improve its adhesion to the gingival when it is used as the crown of the implanted tooth. Hydroxyapatite is the major component of natural bone and has very high bioactivity and thus is selected as the modifier to improve the bioactivity of zirconia. A series of zirconia/hydroxyapatite composites with varied compositions were prepared under different conditions in order to find out the optimal composites for the target application. Various analytical technologies and mechanical tests are employed to characterise structure and properties of resultant composites. Experimental results show that the component ratio and sintering temperature have significant influence on the composite properties. Increase in hydroxyapatite component tends to enhance bioactivity but decline mechanical strength. Experiments found that the composite containing 10% of hydroxyapatite retains sufficient mechanical strength as crown material whilst possesses excellent bioactivity. Sintering results suggest that the optimal mechanical strength is obtained at 1400°C for 2 hours for the composite containing 10% of hydroxyapatite.