When cavities are on visible surfaces of our teeth, they’re relatively easy for dentists to spot. But in between our teeth, especially toward the back of our mouths, dentists typically rely on X-rays to know what’s going on. And X-rays can only catch cavities after about 30% of the tooth enamel in one spot has been compromised. 

Gili Naveh, an associate professor of orthodontics at Tufts University School of Dental Medicine and of biomedical engineering at the School of Engineering, has designed a simple tool, called CaviSense, to help dentists and patients detect tooth decay between teeth before it would ever show up on an X-ray. By catching cavities earlier, dentists can potentially treat and reverse any damage without having to drill out the area and put in a filling. 

“Every tooth that you drill into—the restoration that you make is never for life. It will eventually fail and you will need to replace it and make an even bigger restoration,” Naveh said. “If we can catch cavities earlier and prevent drilling, it will prolong the lifespan of our teeth.”

After practicing dentistry for about six years, Naveh went back to school to earn a Ph.D. in structural biology, followed by a postdoctoral fellowship and an advanced degree in orthodontics. She is now a practicing orthodontist and scientist. In her lab, she usually studies the structure and function of the periodontal ligament—the ligament that connects a tooth to the jawbone—looking for ways to reverse the effects of gum disease and improve orthodontic treatment.

Basic science research like this is vital, but often takes a long time to translate into tangible benefits for patients. When the parents of one of her orthodontics patients expressed their frustration at the number of fillings that their child kept needing, Naveh saw an opportunity to design a solution that could help patients much more immediately.

“They tried everything their pediatric dentist told them, but every time they would go for an exam, the dentist would find so many new cavities,” Naveh said. “They told me, ‘If we could just test at home and see when these early-stage cavities are starting, then we could get to the dentist on time instead of needing three to five fillings each trip.’” 

The tool these parents were wishing for didn’t exist yet, but Naveh had an idea of how to detect cavities before they would show up on an X-ray. Cavities are the result of the wrong kinds of bacteria building up on our teeth. These bacteria consume sugars and produce acids that will cause tooth enamel to dissolve—a process called demineralization—and eventually create a cavity if left untreated. 

Demineralization starts when the pH on a tooth’s surface is less than 5.5 (our mouth is usually fairly neutral, about a pH of 7), so Naveh designed the CaviSense toothpick to detect when the acidity crosses that threshold. 

Before using a CaviSense toothpick, patients are given a sugary gummy to eat. Any troublesome bacteria on the teeth will quickly start digesting this sugar and secreting acids. Then, a dentist or parent can slide the thin, flat tip of the toothpick between teeth or anywhere else that they are concerned about potential tooth decay. If the end of the toothpick changes color from purple to yellow, it indicates that the local pH is below 5.5—acidic enough to dissolve tooth enamel. 

“It’s cheap and it’s easy to use and it’s very visual,” Naveh said. “Both the dentist and patient can see that there is a surface between the teeth that is demineralizing, and some patients appreciate an objective tool that they can see with their own eyes.”

When dentists catch tooth decay early, they don’t necessarily need to put in a filling. In fact, tooth decay can be reversed in some cases with a remineralization treatment, where the dentist cleans away the bacteria and applies a high-mineral paste to the area that helps the enamel solidify again. This process is simpler and less expensive than filling a cavity, as well as being much more pleasant for the patient. 

“There’s no drilling, no filling, no anesthetics—you just apply some polish on the tooth and let it work,” Naveh said. “It’s better for everybody."

Naveh started designing the CaviSense toothpick in her lab, and helped found a startup to bring it to market last year. She and her colleagues at CaviSense, Inc. have been working with pediatric dental practices to add CaviSense to their workflow and ensure that it is useful. The toothpicks are also available for people to use at home, along with an app to help users record and interpret their results. People can purchase five toothpicks for $25 on the CaviSense website.

The CaviSense toothpicks are primarily intended for detecting cavities between teeth, but Naveh and her colleagues know that some parents would like to be able to check every tooth surface at home (which would require a lot of toothpicks). She and her colleagues are in the process of designing an even simpler at-home test, using a fillable tray that a patient would bite into to test all tooth surfaces at the same time. The filler material has the same color-changing properties as the CaviSense toothpick, so any trouble spots will turn yellow in the imprint. 

The researchers are currently in the last stages of making prototypes and intend to start getting feedback from dentists soon. They hope to have this new cavity tester available to consumers by the middle of 2025.

“We can enable people to test whether they have cavities from home, and then get to the dentist in time to stop cavities and even heal the tooth,” Naveh said. “Everybody will be happier—kids, parents, and even dentists because they’ll be able to provide quicker, better treatments to help more patients.”