Study of Apatite Deposition in a Simulated Body Fluid Immersion Experiment

SYNOPSIS The present study evaluated the influence of two different placement orientations of biomaterials on apatite deposition behaviors during immersion in simulated body fluid (SBF). Titanium (Ti) and thin carbonate-containing hydroxyapatite coated Ti (CA/Ti) were used as biomaterials, and Hank’s balanced salt solution was employed as an SBF. Ti and CA/Ti disks were placed either horizontally or vertically. For the horizontal placement, the disks were placed directly on the bottom of the container. For the vertical placement, the disks were hung from a nylon wire. The medium and container were replaced every day. After immersion for 3, 7, and 14 days, the surface appearances of the horizontal or vertical sides of the Ti and CA/Ti disks were observed using a scanning electron microscope. Ti disks showed apatite deposition after 3 days of immersion with the horizontal placement, but few disks showed this with the vertical placement. The Ti surface of the horizontal side was completely covered with deposited apatite. Even after 7 and 14 days, the whole Ti surface of the vertical disk was not completely covered with deposited apatite. For CA/Ti, apatite deposition was clearly recognized after 3 days of immersion on the surfaces of not only the horizontal placement but also the vertical placement. Piled up apatite globules were observed on the horizontal surface, but no distinct piled up globules were observed on the vertical surface after 7 and 14 days of immersion. In conclusion, it revealed that apatite deposition and apatite crystal growth were influenced by the placement orientation of sample disks in SBF immersion experiments.