ALTERATION OF HYDROXYLAPATITE COATINGS EXPOSED TO CHEMICALS USED IN HISTOLOGICAL FIXATION

Histological evaluation of retrieved devices allows for assessment of the biological response to the implants. Interaction between the bioma terial and the fluids used in the processing may alter the appearance or composition of the device. This may result in artifacts due to proc essing which are misinterpreted as being caused by the biological resp onse. Alteration by the fluids used in fixation may be particularly im portant with materials that have a propensity to interact with aqueous environments, as in the case of calcium phosphate ceramics. Therefore , we examined the effects of various standard histological fixation te chniques on hydroxylapatite coated metal implants. Of the techniques e xamined, fixation with ethanol appeared to affect the surface morpholo gy the least, whereas fixation in unbuffered formalin appeared to affe ct the bulk composition of these samples the least. Fixation in buffer ed formalin resulted in marked changes in both surface morphology and bulk composition. (C) 1994 John Wiley and Sons, Inc.