Silver Proves Sterling in Fighting Implant Infections



Despite significant advances in implant technology and procedures, 8% of implants fail within a decade, according to the University of Gothenberg. Infections caused by bacteria and other issues often are what put these implants at risk, say scientists with the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Bremen, Germany.

So, IFAM has developed a plasma implant coating that uses silver ions to kill pathogens. By preventing the growth of bacteria, the DentaPlas coating enables implants to properly take hold and form a faster and more permanent bond with the jawbone. The innovation combines surface materials that feature physical and chemical properties alike.

“We have given the DentaPlas coating a rough texture, which promotes cellular growth, in addition to combining it with a hydrophilic plasma polymer coating, which attracts moisture,” said Dr. Ingo Grunwald, project manager at IFAM.

Silver nanoparticles integrated into the thin plasma polymer coating, which is up to just 100 nm thick, dissolve over the course of several weeks. During that time, the nanoparticles continually release small quantities of anti-microbial silver ions that kill bacteria.

“The DentaPlas system consists of 3 layers, with 2 plasma polymer layers surrounding a center layer of silver. Within this structure a biocide reservoir is formed, and the outermost layer releases the ions,” said developer Dr. Dirk Salz. “This is beneficial because it prevents direct contact between the tissue and the silver particles, which can be toxic when exposed.”

The silver concentration, the thickness of the layers, and their porosity all can be adjusted so the silver ions can penetrate the outermost plasma polymer layer over whatever period of time is considered necessary to properly integrate the implant. Once the silver reservoir is exhausted, no more silver ions are released, preventing long-term toxic effects.

Also, the DentaPlas coating is fully biocompatible and sterilizable as demonstrated in trials using finished implants and titanium test samples that were coated using a plasma polymerization facility. Researchers confirmed the coating’s mechanical stability and robustness in trials using the lower jawbones of pigs taken from butcher ships, screwing coated implants into place using modern dental instruments.

Bio Gate AG, a Fraunhofer spinoff and project partner, has successfully transferred the processes of coating the test samples and titanium screws to its own production facilities. The spinoff also is the manufacturer of the DentaPlas 3-layer coating system and is offering demonstration units.

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