Three Dimensional examination of Bone-Implant interface using various implant materials

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Bone-implant interface must be fully understood. Numerous studies about that have been reported. However, that remains unclear since the studies were based on limited numbers of histological sections. There is little information on the three dimensional bone structure around the implant. Therefore, we developed a new computer-aided system for the three dimensional bone structure around the implant. This system could present not only three dimensional view of bone around the implant, but also bone contact rate and bone volume rate around the implant. Using this system, Bone reactions of three types of implants, dense hydroxyapatite implant, commercially pure titanium implant and calcium mixed titanium implant, were compared. There implants were inserted in the tibiae of male New Zealand white rabbits. Rabbits were sacrificed on 2,4,6 and 8 weeks after implant placement. Removed specimens were reconstructed on the personal computer. From reconstructed 3D model, contact rates at bone-implant interface and bone volume rate around the implant were measured. The results were folllowings. :1) The contact rate of hydroxyaapatite implant increased up to 56% in 4 weeks after and then decreased to 39% in 8 weeks, whereas that of titanium implant increased gradually from 42% in 2 weeks to 60% in 8 weeks.2) The contact rate of hydroxyapatite implant in 2 and 4 weeks after implantation was higher than that of titanium implant, and then declined in the 6 and 8 weeks.3) In calcium mixed titanium, both the contact rate and the bone volume rate were intermediate between those in hydroxyapatite and titanium implant.