Study on plasma sprayed coating of bioactive ceramics onto silicon nitride as implant biomaterials

The success of implants depends on the properties of the material used. It is important for dental implantology to study and produce implant biomaterials with excellent properties. In this study the relation between heat treatment for 1 hour at 580°C after plasma spraying and the crystallinity and solubility of different calcium phosphate coatings is reported. The surface of the coatings were characterized before and after heat treatment after incubation in Gomori´s buffer with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The solubility of the different coatings was compared with the degree of crystallinity. The result was that the post-heat treatment influences the degree of both crystallinity and solubility significantly. Incubation of the coatings in Gomori´s buffers introduced precipitation at the surface of all non-heat-treated coatings of hydroxyapatite (HA) except fluoroapatite (FA). No precipitation could be observed in any of the heat-treated coatings. FA proved to be more stable than HA. Bond strength between the FA or HA and silicon nitride is higher than that of FA or HA and titanium. There is no significant difference in push-out tests of FA and HA