Going to the dentist is an ordeal for most: that cringe-worthy sound of metal scraping your teeth clean, the dreaded news that you have to get a root canal.
But soon, dentistry will change for the better. Sophisticated nanoparticles will protect your teeth from damage or regenerate damaged parts, making synthetic fillings archaic and obsolete. Heck, they might even save you a trip to the dentist.
Put simply, a nanoparticle is a very tiny substance made from a range of different materials. For use in dentistry, nanoparticles are usually made of silica or calcium phosphate, a compound already found in teeth, along with other chemicals that kill bacteria or minerals to repopulate enamel, depending on the particles’ particular use. They can be injected into individual teeth or spread liberally as a toothpaste, mouthwash, or a thick liquid called a slurry.
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Dental researchers have been experimenting with nanoparticles since the 1970s, and they’re only now starting to be used in clinical practice to diagnose infections in the teeth or gums. The most exciting applications—prevention of disease and tooth regeneration—are nearer, but still on the horizon. Why has it taken so long? It’s partially due to the technical challenges—nanoparticles are so tiny that they could stray from the mouth and cause issues elsewhere in the body.
“Thanks to the small size, they can circulate and accumulate in critical organs in the body, such as lungs or blood vessels or the brain, giving rise to cancer or fibrils triggering diseases like Alzheimer’s,” says Marco Salerno, a materials scientist at the Italian Institute of Technology. Scientists have mostly resolved those issues by imbuing the nanoparticles with new properties to get them to stick better to teeth, but for some applications it’s not yet perfect.
The most feasible and immediate application for nanoparticles is to protect teeth. There are thousands of bacteria that live in your mouth, but some of them can cause serious damage if they get into your gums through lack of flossing or if they wear down tooth enamel because you haven’t seen a dentist to scrape away the sticky plaque. That’s one of the big reasons you brush your teeth—to keep the bacteria from settling in. But several researchers have developed a nanoparticle coating that can kill those bacteria, protecting the teeth surface and preventing gum disease.
“[The nanoparticles] are designed to stick to the tooth structure, so the bacteria already there would be slowly eliminated,” says Anil Kishen, a professor of dentistry at the University of Toronto who has developed protective nanoparticles in his lab.
Other nanoparticles could regenerate enamel, teeth’s hardest outer layer. Enamel protects teeth from extreme temperatures and potentially damaging chemicals that would cause cavities, but it gets worn down over time (toothpastes and mouthwashes contain fluoride to slow its erosion).
“Enamel is 98 percent pure mineral, and it’s just sitting there on the surface of the tooth. We don’t know why it doesn’t get regenerated,” says Vuk Uskokovic, a bioengineering professor at the University of Illinois at Chicago. Nanoparticles could restock enamel with mineral molecules, rebuilding some of that mineral layer to keep teeth healthier for longer.
And nanoparticles could prevent root canals and fillings by encouraging broken or infected teeth to repair themselves. Today, if you get a cavity, your dentist will probably fill it with some combination of metals (mercury is often among them) intended to last for 10 or 20 years. But in that time, the fillings can further damage teeth.
“The most common problem we encounter is the interface between the filling material and the tooth—that’s where most cavities appear again because bacteria, water, and organic compounds infiltrate that interface,” Uskokovic says.
Instead, antibacterial nanoparticles could resolve the infection, then help teeth regrow themselves to fill in the holes with its own tissue. “Ideally we could put in this filling and it would simply disappear in three months. Right now we don’t have anything like that,” Uskokovic says. And instead of lasting for decades, the fix would be permanent, strengthening the mechanical properties of the tooth for the rest of a patient’s life.
Eventually, nanoparticles could help totally regrow a tooth, like if one gets knocked out during a hockey game or falls out due to gum disease. We’re still a long way from being able to generate those teeth in an empty socket, Uskokovic says, but even a tooth grown outside the body from a patient’s own cells can then be implanted in the gum. That’s better than totally artificial teeth because your immune system is less likely to attack your own tissues.
While these nanoparticles aren’t available at your local dentist quite yet, they’re not far off; Uskokovic estimates that the cavity-fighting regenerative particles will be in clinics in the next decade or so. Kishen hopes that his antibacterial protective coating will be on the market within the next year and estimates that it won’t cost more than existing fluoride treatments, about $50.
Though nanoparticle researchers are resolving smaller issues like scaling up production and extending the particles’ shelf life, they are still having trouble convincing the dental establishment that nanoparticles are worthwhile. “Dental science is well known in biomaterials as the most resistant to change and innovation,” Uskokovic says.
And that’s difficult when they’re suggesting something so dramatically different. “From a commercial perspective, nanoparticles will be really disruptive,” Kishen agrees, changing a long-established and powerful industry. But when the kinks are finally worked out, there’s little question that patients will benefit from fewer visits to the dentist but overall healthier teeth.
