OSTEOBLAST PRECURSOR CELL-ACTIVITY ON HA SURFACES OF DIFFERENT TREATMENTS

The clinical success of dental implants is governed by implant surface s and bone cell responses that promote rapid osseointegration and long -term stability. The specific objective of this study was to investiga te osteoblast precursor cell responses to hydroxyapatite (HA) surfaces of different treatments. Since the nature of bone cell responses in v itro is influenced by the properties of HA ceramics, this study was di vided into two components: a chemical and crystallographic characteriz ation of the HA ceramics and an in vitro cell culture study. The sinte red HA samples were observed to have the highest crystallite size as c ompared to the as-received HA and calcined HA samples. No differences in the surface roughness and chemical composition were observed among the sintered, calcined, and as-received KA surfaces. In concurrence wi th the X-ray diffraction, high resolution XPS resolution of Ca 2p also indicated a higher crystallinity on sintered HA samples as compared t o the calcined and as-received PIA samples. As indicated by increased alkaline phosphatase-specific activity, increased cell-surface and mat rix-associated protein, and 1,25 (OH2) vitamin D-3-stimulated osteocal cin production, a more differentiated osteoblast-like phenotype was ob served on the sintered HA surfaces compared to the as-received HA and calcined HA surfaces. An increased osteoblast-like cell activity on th e sintered HA surfaces suggested that the crystallite size of HA surfa ces may play an important role in governing cellular response. (C) 199 8 John Wiley & Sons, Inc.