[Improvement of osseointegration of titanium dental implant surfaces modified with strontium-substituted hydroxyapatite].
OBJECTIVE
To explore the osteogenic activity of a micro-arc oxidation (MAO)-treated strontium (Sr)-substituted hydroxyapatite (Sr-HA) coating developed to enhance the osseointegration of titanium dental implants, and to investigate the strengthening mechanisms of bone bonding of crystalline hydroxyapatite (HA) with incorporation of strontium in vivo.


METHODS
The morphology and phase component of the oxidized film of Sr-HA and HA coated implants were examined by SEM and X-ray diffraction (XRD). Then, twenty-four implants were inserted into the metaphysis of rabbits tibias and femurs using polyfluorochrome sequential labeling. Four and 12 weeks following the surgery, the morphology and chemical composition of the bone-implant interfaces were evaluated by histological examination and energy-dispersive X-ray.


RESULTS
The XRD patterns showed that diffraction peaks of HA shift to lower 2θ values with Sr-addition, which resulted in decreases in lattice energy and then crystallinity. Sr-HA coating presented a microporous structure in the SEM observation. Meanwhile, Sr-HA coating exhibited osteogenic activity at the early stage of bone healing period and new bone mineral apposition ratio [(4.75 ± 0.46) microm/d] was significantly higher than that of the control group [(3.21 ± 0.44) microm/d]. An apatite layer was observed at the interface of bone-Sr-HA coating in light microscopy observation and energy-dispersive X-ray analysis. Then the apatite layer was precipitated and formed new bone which became mature bone and bonded tightly to the Sr-HA.


CONCLUSIONS
Strontium-substituted hydroxyapatite coating shows high biological activity, which can accelerate the formation of apatite layer, hence the osteogenic ability.
Yan
Jun
J
Department of Prosthodontics, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China.
Zhang
Yu-mei
YM
Han
Yong
Y
Zhao
Yan-tao
YT
Sun
Ji-feng
JF
Yan
Hao
H
D000818:Animals; D001031:Apatites / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D001840:Dental Bonding; D015921:Dental Implants; D006882:Hydroxyapatites / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration; D011817:Rabbits; D011897:Random Allocation; D013324:Strontium / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium; D014961:X-Ray Diffraction
D001031:Apatites; D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D006882:Hydroxyapatites; C076185:strontium hydroxyapatite; D014025:Titanium; D013324:Strontium