含锌磷酸钙活性涂层钛种植体骨整合性能研究

Osseointegration properties of titanium implants with active zinc-containing calcium phosphate coatings

目的:探讨低含量锌加入钛种植体表面涂层后对骨整合的影响。方法:随机将钛种植体分为PEO-Zn组(n=36)和PEO-Ca/P组(n=36),应用等离子体电解氧化法(PEO)在其表面制备磷酸钙活性涂层,PEO-Zn组采用含锌涂层,PEO-Ca/P组为不含锌的涂层。应用场发射扫描电镜观察两组涂层表面形貌,X线衍射仪分析涂层晶相结构。将种植体72颗植入18只日本大耳白兔双侧下颌骨,每侧2颗。术后对大耳白兔进行双荧光标记,分别于植入术后4周、8周与12周取两组带种植体的骨组织,应用荧光显微镜观察新骨形成,采集图像测量荧光条带间距计算骨矿化沉积率;应用亚甲基蓝-碱性品红法染色观察骨组织与种植体结合长度,计算骨接触率。结果:扫描电镜可见两组等离子体电解氧化膜内层致密,外层呈粗糙的多级孔洞状结构。X线衍射仪分析显示PEO-Ca/P组中钙元素主要以CaO和羟基磷灰石(HA)存在,PEO-Zn组中锌元素主要是以Zn 3P 2和ZnO存在。各时间点两组种植体周围均显现二甲酚橙与钙黄绿素标记的荧光带,呈条状,两荧光带间距离明显。植入后4、8、12周PEO-Zn组的骨矿化沉积率均高于PEO-Ca/P组(5.25±0.59比4.79±0.43,4.62±0.54比4.18±0.50,4.90±0.54比4.44±0.53,均P<0.05),4周时PEO-Zn组骨矿化沉积率最快(P<0.05)。两组种植体在植入后各时间点均能与骨组织不同程度紧密连接,呈骨性结合。植入后4、8、12周PEO-Zn组的骨接触率高于PEO-Ca/P组(32.69±7.43比28.06±8.15,51.95±5.41比47.03±6.13,73.91±8.15比61.73±11.84,均P<0.05),12周时PEO-Zn的骨接触率最高(P<0.05)。结论:PEO法制备的含锌磷酸钙涂层,提高了种植体生物活性,加速了骨组织的形成与改建,促进了种植体-骨界面的整合。

Objective:To investigate the effect of low-content zinc on osseointegration when added to the coatings of titanium implant.Methods:Plasma electrolytic oxidation(PEO)was used to prepare active calcium phosphate coatings of titanium implants.Then,the itanium implants were randomized to the PEO-Zn group(zinc-containing coatings,n=36)and PEO-Ca/P group(zinc-free coatings,n=36).Field emission scanning electron microscopy(FE-SEM)was used to observe the surface morphology,and X-ray diffractometry used to analyze the crystal structure,of the two coatings.Seventy-two implants were implanted bilaterally into the mandibles of 18 Japanese big-ear white rabbits,two on each side.After operation,the two groups of big-ear white rabbits were double-fluorescently labeled,and harvested for implant-containing bone tissue at weeks 4,8 and 12,respectively.The specimens were observed for new bone formation under a fluorescence microscope.Bone mineralization was calculated according to the fluorescent band spacing measured from acquired fluorescence images.Bone implant contact(BIC)was calculated according to the length of bone tissue in direct contact with the implant,as observed by methylene blue-alkaline fuchsin staining.Results:FE-SEM showed that,in either group,PEO films presented a dense inner layer and a rough,multi-level porous outer layer.X-ray diffractometry showed that the calcium element in the PEO-Ca/P group was mainly in form of CaO and hydroxyapatite(HA),and the zinc element in the PEO-Zn group was mainly in form of Zn 3P 2 and ZnO.At each time point in either group,the strip-like fluorescence bands labeled by xylenol orange and calcein were displayed around the implants,with obvious spacing between bands.At weeks 4,8,and 12 after implantation,the bone mineralization was higher in the PEO-Zn group than that in the PEO-Ca/P group(5.25±0.59 vs 4.79±0.43,4.62±0.54 vs 4.18±0.50,4.90±0.54 vs 4.44±0.53,all P<0.05),and was fastest at week 4 in the PEO-Zn group(P<0.05).At different time points after implantation,the implants in either group were bound to the bone tissue by osseointegration in varying degree of tightness.The bone implant contact rates were higher in the PEO-Zn group than that in the PEO-Ca/P group at weeks 4,8,and 12 after implantation(32.69±7.43 vs 28.06±8.15,51.95±5.41 vs 47.03±6.13,73.91±8.15 vs 61.73±11.84,all P<0.05),and was the highest in the PEO-Zn group at week 12(P<0.05).Conclusion:The zinc-containing calcium phosphate coatings prepared by PEO improves the biological activity of the implant,accelerates the formation and remodeling of bone tissue,and promotes the osseointegration at the implant-bone interface.