Killer silicon nitride: Bioceramic slaughters bacteria, could now help fight gum disease | The American Ceramic Society

Killer silicon nitride: Bioceramic slaughters bacteria, could now help fight gum disease

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[Image above] Credit: marissa anderson; Flickr CC BY 2.0

Silicon nitride is a killer ceramic material.

Its antibacterial properties are one of many reasons why the material has found its way into biomedical implants and devices, including various components manufactured by a company that specializes in biomedical silicon nitride, Amedica Corp. (Salt Lake City, Utah).

Amedica has done a lot of research on silicon nitride’s superior biomedical performance, including studies assessing the material’s wear resistance and osteoconductive and antimicrobial properties.

And in addition to preventing growth of potentially dangerous bacteria, silicon nitride may soon have another benefit—the ability to fabricate patient-customized implants.

Amedica recently announced that it is first to 3-D print medical silicon nitride structures. The company developed a method to generate silicon nitride biomedical components using robotic deposition, or robocasting, which deposits colloidal slurries of the material in freeform layers, sans binder.

According to the press release, the company “can now progress toward commercializing 3-D printed silicon nitride implants, with controllable porosity levels to address specific clinical needs.”

Amedica already fabricates a variety of silicon nitride products for orthopedic applications and has received FDA clearance for some of its products, including ceramic interbody vertebrae fusion devices. The company says it is working on development of joint replacements made of silicon nitride, too.

And according to a press release from the American Chemical Society, silicon nitride’s super antibacterial abilities may soon bring the material into your mouth, too.

The new research shows that silicon nitride’s antibacterial abilities extend to gum disease-causing bacteria.

Not all bacteria are created equal—and because there are so many species of bacteria and they can evolve so rapidly, what is effective at thwarting one species may have no effect on another.

The new research reports that tests with Porphyromonas gingivalis bacteria, one of the species predominant in gum disease, show that not only does silicon nitride stop bacterial growth, but it also slaughters the bacteria on the material’s surface.

Gum disease is a health concern because it can cause significant complications that reach beyond just poor oral health and tooth loss. Gum disease has a negative impact on overall human health, with potential effects reaching as far as heart health and systemic inflammation.

So keeping your mouth clean, and keeping disease-causing microbes at bay, is an important overall public health issue. And bioceramics can help.

But how does silicon nitride do the trick? The new research shows that the surface of silicon nitride bioceramics chemically induces the demise of bacteria.

More specifically, pH-dependent surface chemistry of the bioceramic alters bacterial metabolism, causing the microbes to generate peroxynitrite—which in turn generates free radicals that kill the microbes themselves.

Through their experiments, the researchers found that altering the surface of the bioceramic—by chemical etching or thermal oxidation—had varying effects on bacterial metabolism, too. This detail suggests that scientists may be able to tailor the surface of silicon nitride implants to effectively prevent bacterial complications.

The paper, published in Langmuir, is “Silicon nitride bioceramics induce chemically driven lysis in Porphyromonas gingivalis” (DOI: 10.1021/acs.langmuir.6b00393).