Hydroxyapatite-electroplated cp-titanium implant and its bone integration potentiality: an in vivo study

This study was designed to precipitate hydroxyapatite coating on the surface of commercially pure titanium (cpTi) implants using an electroplating technique. After characterization of the hydroxyapatite coating, the bone-implant interface and bone integration of both cpTi and hydroxyapatite-coated implants were assessed.

Twenty implants were divided equally into 2 main groups (n = 10). Ten cpTi implants were utilized as received, while the others were hydroxyapatite coated and then sterilized. The implants of both groups were inserted in the tibiae of New Zealand rabbits. The purity and crystallinity of the hydroxyapatite coat were characterized using x-ray diffraction. A scanning electron microscope examined the grain morphology. Profilometer evaluated the surface texture before and after sterilization. Histological examination using a scanning electron microscope was performed to qualify osseointegration of the regenerated bone and measure the gap distance at the bone-implant interface.

Pure crystalline hydroxyapatite precipitate of thickness (range 69-78 microm) and rough surface (2.7 +/- 0.2 microm) compared to smooth cpTi (1.3 +/- 0.5 microm). The gamma-radiation sterilization resulted in finer grains and insignificant smoother surface. Histological examination of the cpTi implant exhibited less bone regeneration with few and less dense bone trabeculae, and gap distance was significantly high (1.29 +/- 0.51 microm). Meanwhile, the hydroxyapatite-coated implant showed a recognizable amount of bone regeneration with more and denser bone trabeculae, and gap distance ranged from 0 to 1.32 microm.

The employed technique provided a thin and uniform pure crystalline hydroxyapatite coating. The characterization of the precipitated film is promising for clinically successful long-term bone fixation.