Teeth-cleaning robots, red-light therapy: What’s ahead for dental health

That future is getting closer, scientists say. “We are really looking for disruptive technology," says Dr. Hyun (Michel) Koo, co-founding director of the Center for Innovation & Precision Dentistry at the University of Pennsylvania.

Here, brush up on the latest discoveries that could transform your oral health.

Teeth-cleaning microrobots

A swarm of microrobots could clean your teeth for you.

It is a three-in-one solution, says Koo. In an automated system, the swarm acts as a toothbrush, flosser and mouthwash.

Koo and Edward Steager, a senior research investigator at the University of Pennsylvania’s School of Engineering and Applied Science, have led development of the microrobot technology, which uses tiny particles known as nanoparticles—in this case from iron-oxide compounds. These nanoparticles are approved by the Food and Drug Administration for uses ranging from imaging to food coloring, thanks to their ability to take on a red, yellow or brown shade.

“You can eat them," Koo says. These particles can also come together to form a microrobot, a small device that can complete a complex task. Magnets guide the microrobot swarms to form different shapes, from bristles for brushing to an elongated thread for flossing. With a push of a button, the oral routine is automated by programming when and where these magnets turn on.

There are two prototypes: a mouthguard-like device and a toothbrush-like device. You turn on the magnets and inject a solution containing the microrobots and hydrogen peroxide, a common cleaning agent. The microrobots act like a disinfecting mouthwash when combined with hydrogen peroxide. By chemically activating the hydrogen peroxide, the nanoparticles kill bacteria and break down plaque more effectively than the disinfectant alone, Koo says. The system can remove 100% of plaque on a 3-D printed model of human teeth and gums, and 80% in animal testing. They hope to improve the latter number as they wrap up their trials in animals by the end of 2024.

Another challenge they are working on is shortening the time of the routine, which now takes between five and 10 minutes, Steager says. The current prototype would cost less than a fancy electric toothbrush, Koo says. This is estimated based on the device using simple electronics and low-cost nanoparticles that they can make in their lab. Researchers see the initial market as people with disabilities who have difficulties brushing their teeth, though they also see eventual uses for people looking for convenience. “I have a son who hates brushing his teeth," Koo says.

Mouth bacteria as medicine

One person’s mouth bacteria might be another’s medicine. That is the idea behind oral microbiota transplants: transfers of bacteria from the mouth of a healthy donor to a patient. Scientists at Pennsylvania State University and the University of Adelaide believe this treatment could one day curb tooth decay and gum disease.

We each have around 200 species of bacteria in our mouths, with the exact distribution depending on diet, genetics and lifestyle, according to Laura Weyrich, an associate professor at Penn State who leads a team developing this treatment. Different bacteria can either cause oral disease or prevent it. The team hunted for two years for a “super donor"—somebody with the best balance of good and bad mouth bacteria and no tooth decay or gum disease. They chose a young adult who only brushes their teeth once a day, never flosses and hasn’t seen a dentist in five years—yet has no cavities. This person’s microbiome was so healthy, such oral hygiene habits didn’t matter, says Dr. Sonia Nath, a researcher at the University of Adelaide.

The scientists took plaque—the gunk that coats teeth and gums—from the donor’s mouth, mixed it with gel and painted it on the teeth of rats. The rats showed a significant drop in tooth decay. The team aims to start clinical trials in humans in 2025. Beyond finding out if the transplant works in people, the researchers are studying whether the same transplant will work across different demographics and how often it must be renewed. The treatment would likely need to be stored at very low temperatures, and the scientists envision an application every few months at a dentist’s office. “You get a quick transplant, and then you’ve got your mouth sorted," Weyrich says.

Red-light therapy for your gums

Imagine a tooth implant with built-in technology to deliver immune-boosting red-light therapy. It doesn’t even need a battery—the light is powered by the movements of your mouth.

Tooth implants carry the risk of peri-implantitis, a bacteria-driven disease that destroys the gum and bone tissue around the implant. Geelsu Hwang, an associate professor in the department of preventive and restorative sciences at the University of Pennsylvania, thinks he has a solution in a high-tech dental implant that emits light to the gum around an implant.

Hwang’s team found that both red and near-infrared light stimulate gum tissue to release antimicrobial peptides, proteins of the immune system that kill bacteria. They went with near-infrared light, which is invisible. “I’m pretty sure not many people would like to have a visible red light from their mouths," Hwang says. The light targets the gum around the implant to help it fight off bacteria that would normally breed infection.

The artificial tooth is made of barium titanate, what is called a piezoelectric material, which generates electricity in response to physical stimulation. Motions such as chewing help power the implant’s light-therapy LEDs. The barium titanate also naturally wards off bacteria. One drawback is that it isn’t as strong as zirconia, a ceramic material commonly used for implants. Hwang says the team is working on strengthening it.

In the lab, they tested their light therapy on gum-tissue cells surrounded by disease-causing bacteria and found 90 minutes of daily light was sufficient to minimize inflammation. They are also investigating whether the treatment needs to be continuous or can be broken up.

The product will be tested in pigs later this year, with the goal of moving to human clinical trials.

Rebuilding enamel

Can scientists engineer stronger, less sensitive teeth?

Enamel, the hard outer layer of a tooth, protects teeth from damage. But the body can’t regenerate it once it is eroded, and dentists can’t replace it either. Scientists are working on a gel that rebuilds enamel by copying mother nature.

Such a technology has long been a dream for many, says Janet Moradian-Oldak, a professor of biomedical sciences and bioengineering at the University of Southern California who leads a team working on it. She spent the past 25 years studying the proteins that build enamel, with a special interest in one called amelogenin.

Our bodies use amelogenin early on in our teeth development to organize calcium and phosphate—two minerals that constitute the bulk of enamel—into layers. The process is similar to laying bricks: Amelogenin arranges calcium and phosphate into an organized, repeating pattern. In 2016, Moradian-Oldak and her team had a breakthrough when they designed a peptide—a shorter chain of amino acids—based on amelogenin that successfully mimicked its function. When that peptide was put in a gel and painted on the surface of extracted wisdom teeth, a new enamel-like layer formed. The peptide also remineralized dentin, the layer underneath enamel.

The idea of using a peptide to rebuild enamel is something a number of researchers have been working on, with teams at the University of Washington and universities in China developing similar technologies.

In traditional treatments, fluoride works by forming patches of mineral deposits on the surface of the tooth. But that doesn’t preserve the strength and physical properties of enamel as well as the structured layers created by the gel, Moradian-Oldak says. Meanwhile, toothpastes containing calcium and phosphate provide the basic building blocks for mineralization, but they don’t have the peptide needed to build organized layers.

Moradian-Oldak hopes the gel can prevent the progression of tooth decay by rebuilding lost enamel. She sees use for patients with tooth hypersensitivity, dental erosion, areas of demineralization called white spot lesions and a genetic disorder called amelogenesis imperfecta where enamel forms incorrectly. There is a chance the gel could whiten teeth, too, by forming a new layer over the entire surface, but her team hasn’t done any experiments testing for this, so “this is just an idea," she says.

Limitations remain: For example, it takes at least 16 hours to grow one organized enamel-like layer, and each layer is thin—for reference, it would take hundreds of these layers to match the thickness of natural enamel. “We still need to make them thicker, stronger," she says.

Moradian-Oldak says she secured patents for her gel and is now in the process of applying for FDA approval to start clinical trials.

A drug to grow teeth

An innovative drug could regenerate missing teeth.

In mice with congenital tooth agenesis—a condition where teeth are absent as a result of failed development—one intravenous injection of this drug allowed teeth to form. The new drug is an antibody designed to block a protein called USAG-1 that normally stops extra teeth from growing. Blocking the protein allows tooth buds, the first stage of tooth formation, to mature.

“One molecule has potential to make a whole tooth," says Katsu Takahashi, head of the dentistry and oral-surgery department at Kitano Hospital in Osaka, Japan, who is leading the project.

His team’s first human trial, planned for the fall, will test for safety, rather than tooth growth, in healthy adults. If that trial succeeds, they will move on to test the drug on children ages 2 to 7 who are missing teeth because of congenital tooth agenesis.

Takahashi says children with this disease have the beginnings of tooth buds that don’t develop properly due to genetic and environmental factors. The team hypothesizes the drug could allow the formation of permanent teeth. The trial would take three to five years, the typical time it takes to grow a permanent tooth from the bud stage in the jaw to eruption through the gum.

The team will also continue its basic research in hopes of expanding the drug’s potential uses to adults, Takahashi says.