To observe the early bone response of the endosseous implants with different surface roughness in the gap-healing model.
Methods:
A total of twenty implants with a round depression were placed in the distal femur condyles of 10 rabbits. Ten implants were machined (MA) surface and the other ten were sandblasted/acid-etched (SA). Calcein and alizarin were applied intramuscularly respectively at 5 days and 19 days after operation. After 30 days of healing, the rabbits were sacrificed and the samples were treated with the nondecalcification technique. Then fluorescence was observed with laser scanning confocal microscope. And histomorphometric analysis was performed after fuchsin-methylene blue double staining.
Results:
In the gap healing sections of some SA implant cases, green fluorescence zones were observed both at the break end of the trabecular bone and on the depressed surface of the implant respectively, while the red fluorescence areas connected the green fluorescence zones around 19 days after operation. However, in MA implants, green fluorescence zones were less than their equivalent SA implants. Histochemical observation revealed that de novo bone was widely spread on the surface of SA implant. Nevertheless, in some areas of MA surfaces gaps of hundreds of microns are present between the implant and bone. Moreover, SA implant showed significantly higher bone-to-implant contact than MA implant by histomorphomitric analysis.
Conclusions:
Two kinds of bone formation, distal osteogenesis and contact osteogenesis, exist in bone-implant interface during the bone healing process, which form toward each other to promote osseointegration. Surface roughness positively affects the contact bone formation during osteointegration process.
Acknowledgements:
This study was supported by funds from the National Natural Science Foundation of China (No. 30300392 ) and the Innovation Research Programs by College Students of China(No. 071048659).