Effects of Ion Beam-Assisted Deposition of Hydroxyapatite on the Osseointegration of Endosseous Implants in Rabbit Tibiae

The aim of this study was to evaluate the effects of coating implants with hydroxyapatite (HA) by an ion beam-assisted deposition (IBAD) method and to compare them with implants prepared with sandblasted and machined surfaces. Examination of osteoblast cultures displayed no difference in the secretion of alkaline phosphatase (ALP) between the various surfaces, but the IBAD-HA specimen showed low ALP secretion (P .05). Removal torque tests showed that implants coated with HA by the IBAD method had values similar to the implants with a sandblasted surface, but values for the machined-surface implants differed. Implants placed in a group of ovariectomized rabbits showed lower mechanical test values than implants placed in sham-operated rabbits (P .05). Implants coated with HA by the IBAD method demonstrated the highest mean bone-to-metal contact ratio on all threads and on the 3 best consecutive threads, followed by the implants with a sandblasted surface and implants with a machined surface (P .05). Hydroxyapatite-coated implants showed a slightly higher bone-to-implant contact ratio than sandblasted implants, but no statistically significant difference was seen between the 2 materials. The implants placed in ovariectomized rabbits showed lower amounts of bone-to-metal contact than the implants placed in sham-operated rabbits, but no statistically significant difference was seen between the 2 groups. Evaluation of bone volume on all threads and the 3 best consecutive threads showed no statistically significant difference among the different surface treatment groups, but lower bone volume was seen in the ovariectomized rabbits than in the shamoperated animals (P .05).