Abstract: ［Abstract］  Objective〖HTSS〗〓To investigate the effect of lanthanumhydroxyapatite composite coating on osseointegration of the bone around titanium screw.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Nine New Zealand white rabbits were divided into two groups randomly(6 as in experimental grap and 3 in control group). After removing the 4 upper and lower incisors, the sockets were filled with xenogeneic freezedried bone. Then in experimental group, the titanium screw with lanthanumhydroxyapatite composite coating was implanted into socket immediately. In control group, the titanium screw with hydroxyapatite coating was taken the same procedure as in experimental group. The animals were executed respectively at 4 th, 8 th and 12 th week after operation, and the intact maxillary and mandibulary were harvested to be observed, and tested by gross observation, bone density analysis, torque test, and histological observation.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓In the two groups, the average gray values of the new bone near the titanium screw and the torque peak values of titanium screw were gradually increased with the time extension. And at the same time point of 4 th, 8 th, 12 th week after operation, the average gray values of the new bone near the titanium screw and the torque peak values of titanium screw in experimental group were higher than those of control group（P＜005）. The regenerated osseous tissue in experimental group shows an earlier formation and higher maturity of the lamellar bone than that in control group.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓Under the condition of immediate implantation, hydroxyapatite coating and lanthanum hydroxyapatite composite coating can be used to obtain good osseointegration and bone repair of titanium screw and surrounding bone tissue. However, the lanthanum hydroxyapatite composited coating has better biological stability and biocompatibility, which can promote the osseointegration of titanium screw.

Key words: dental implantation, hydroxyapatites, lanthanum, rabbits