1999 Volume 12 Issue 1 Pages 55-63
Between 1992 and 1996 a total of 1597 hydroxylapatite coated cylinder type implants were placed in maxillary and mandibular locations. Fifty eight implant bodies were removed due to excessive bone resorption. Of these,12 were examined in terms of changes in the surface morphology and physical chemistry of the hydroxylapatite layer. Optical microscopy and SEM were employed to study surface and cross sectional features. Wide angle x-ray diffraction was used to determine the crystalline structure of the hydroxylapatite layer. In addition, elemental analysis to ascertain its chemical composition was performed using energy dispersed x-ray spectrometry. Examination of the hydroxylapatite layer of failed implants revealed contamination of the coating including an increase in the transparency of the layer which was in contrast to the characteristic white surface fo new implant body. Although significant changes were not observed in thickness or chemical composition of the HA coating changes in the crystalline structure of failed implants suggested amorphization of the hydroxylapatite.
