Researchers at North Carolina State University have developed a "smart coating" that helps dental and other surgical implants bond more closely with bone and ward off infection.
When patients have hip, knee, or dental replacement surgery, they run the risk of their bodies rejecting the implant. But the new coating developed at North Carolina State mitigates that risk by fostering bone growth into the implant. The coating creates a crystalline layer next to the implant and a mostly amorphous outer layer that touches the surrounding bone. The amorphous layer dissolves over time, releasing calcium and phosphate, which encourages bone growth.
"The bone grows into the coating as the amorphous layer dissolves, resulting in improved osseointegration," said Afsaneh Rabiei, Ph.D., a North Carolina State University associate professor of mechanical and aerospace engineering and co-author of a paper describing the research (Acta Biomaterialia, December 2009).
This bonding also makes the implant more functional, because the bonding helps ensure that the bone and the implant do a better job of sharing the load.
"We call it a smart coating because we can tailor the rate at which the amorphous layer dissolves to match the bone growth rate of each patient," Rabiei said.
The researchers have also incorporated silver nanoparticles throughout the coating to ward off infections. The silver particles act as antimicrobial agents as the amorphous layer dissolves, Rabiei said. This will not only limit the amount of antibiotics patients will need following surgery, but will provide protection from infection at the implant site for the life of the implant.
Moreover, the silver is released more quickly right after surgery, when there is more risk of infection, due to the faster dissolution of the amorphous layer of the coating. Silver release will slow down while the patient is healing.
The research was funded by the National Science Foundation and was accomplished with assistance from the Center for Nanophase Materials Sciences and Shared Research Equipment User Facilities at the Oak Ridge National Laboratory.
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