CYTOTOXICITY INVESTIGATIONS OF PLASMA-SPRAYED CALCIUM-PHOSPHATE COATINGS

One-potential alternative material to replace hydroxyapatite (HAp) as a coating material for plasma-sprayed coatings on implants for hip rep lacement is fluorapatite (FAp). FAp has advantages over HAp regarding the capability of being chemically stable during the coating process. This leads to surface coatings containing high apatite rates with a me chanical stability (bond strength, microhardness) comparable to HAp. F rom the technical point of view the production of FAp coatings is well investigated, although studies on biocompatibility of FAp coatings ar e fewer. This paper reports the production of HAp and FAp coatings wit h varying solubilities by plasma spraying and their in vitro cytotoxic ity. Varying solubilities were realized by using modified plasma-spray parameters in common with suitable apatite powders with different cry stallinities. Coating solubilities were evaluated by immersing the pla sma-sprayed coatings in deionized water and electrolyte solution. Afte rwards,, cytotoxicity tests were performed using a modified half-slide technique. Cell attachment and cell morphology were evaluated. Neithe r HAP nor FAp coatings exhibited cytoxic influence on cells in culture . Results suggest that HAp coatings stimulate cell growth and FAp coat ings do not. This could be explained by a negative effect on cell grow th of the dissolved fluoride ions.