多孔型种植体磷酸钙溶胶膜-骨界面的远期观察

The long-term observation for osseointegration of calcium phosphate sol-gel coating on Ti-6A1-4V implants

目的进一步探讨磷酸钙(CaP)溶胶薄膜对多孔型钛合金(Ti-6Al-4V)种植体表面骨生长的远期影响。方法将表面涂有极薄CaP溶胶膜的多孔型钛合金种植体分别植入8只兔的胫骨。种植区愈合第2周、8周、12周、24周后,各取含种植体的骨组织标本,利用反向扫描电镜摄像技术进行形态观测研究。结果术后第2周SEM显示骨组织直接沿磷酸钙溶胶膜表面生长,而且磷酸钙溶胶膜在种植体表面附着良好;术后第8周与第12周,SEM高倍镜下所见相似,在种植体表面磷酸钙溶胶膜与新生骨组织之间形成富含大量钙和磷酸盐的黏合线样层;术后第24周,种植体表面大部分金属颗粒上的磷酸钙溶胶膜已消失,新生骨组织直接附着在钛合金种植体表面。结论远期观察多孔型种植体表面的磷酸钙溶胶膜,未见涂层界面分离现象。磷酸钙溶胶膜不仅有利于促进种植体早期骨结合,而且即使涂层被吸收后也不会影响种植体的稳固性。

Objective To observe the long-term impact of calcium phosphate sol-gel coating on bone growth. Methods The porous-surfaced Ti-6Al-4V implants were prepared with the addition of a very thin film of calcium phosphate through sol-gel coating, and implanted into the tibiae of 8 rabbits. Implanted sites were allowed to heal for 2,8,12 and 24 weeks, then specimens were obtained for SEM analysis using the freeze-fracture SEM technique. Results Through observation at 2nd, 8th and 12th week after implant surgery, SEM micrographs of the sol-gel coated implants recovered by freeze-fracture technique showed extensive bone growth from the endosteum along the implant surface. It could be seen that while the CaP layer was well adapted to the metal substrate, the bone was in direct contact with the CaP layer. The cement line-like layer was dearly demonstrated to be an intervening electron dense afibrillar layer between the Ca-P coat and the overlying newly deposited bone,which was thought to be rich in calcium and phosphate and free of collagen fibers. After 24 weeks of wound healing, the bone was in direct contact with the porous-surfaced Ti alloy, while the CaP layer was rarely found left on the metal substrate surface. Conclusion Based on the findings in the long-term observation,the addition of a thin layer of CaP to these implants promotes an extensive osseolntegrated interface between the porous-surfaced Ti alloy and the newly deposited bone. The stability and osseointegration of the porous-surfaced implants seems not to be affected by the osteoclastic resorption of CaP layer occurring during 24 weeks of healing.