Pigs can regrow their adult teeth. What if humans could, too?

When children lose their baby teeth, there is an adult set already growing beneath the gums, ready to emerge. But if we lose our permanent teeth, there aren’t any more waiting in the wings. Right now, the options for replacing these lost teeth are either dentures or titanium implants, neither of which provide the same function and feedback as a real, living tooth.

Pamela Yelick, AG89, a professor at Tufts University School of Dental Medicine, wants to be able to grow new, living teeth to replace those we’ve lost. In a paper published at the end of 2024 in Stem Cells Translational Medicine, Yelick and her colleagues showed that they could grow human-like teeth in pigs using a combination of human and pig tooth cells. The work is a significant step toward replacing dental implants with bioengineered living teeth.

Dental implants typically have a base of titanium, which is anchored into the jawbone. Titanium integrates well with bone, but it doesn’t have the soft tissue that surrounds a natural tooth root to cushion chewing forces and promote healthy bone turnover, or nerves to provide sensory feedback.

If the implant isn’t perfectly aligned, or a person is chewing too hard, the bone around the implant can start to break down and be absorbed back into the body. This creates opportunities for bacteria to reach the implant, which can accelerate bone resorption and eventually cause the implant to fail.

“Even creating a tooth root that you could put an artificial crown on—with living dental pulp in the middle, secured by periodontal ligaments instead of being screwed into the jaw—could be a huge improvement to a person’s oral health and in turn, systemic health,” says Yelick, who also holds appointments in the Graduate School of Biomedical Sciences and in the School of Engineering.

Prompting the body to grow new teeth isn’t easy. Our teeth start as a tooth bud—a little bulb of cells inside the jaw—which grows and differentiates into all the hard and soft tissues that make up a tooth and connect it to the jaw. The researchers needed to create their own bioengineered tooth bud with the right cell types and instructions to grow into a tooth on its own.

The tooth bud is made of two types of cells: dental epithelial cells, which produce tooth enamel, and dental mesenchymal cells, which eventually form the rest of the tooth, including the dental pulp, dentin, cementum, and periodontal ligament tissues.

Yelick and her team were able to collect dental mesenchymal cells from the pulp of extracted human wisdom teeth and other healthy teeth removed for orthodontic reasons, but dental epithelial cells are only present in the very early stages of tooth development. They can’t be collected from people once our teeth have been formed. They can, however, be collected from unerupted teeth present in pig jaws.

Unlike humans, pigs can grow multiple sets of adult teeth, so their adult jaws contain additional tooth buds. The researchers acquired pig jaws that would otherwise have been discarded from slaughterhouses and were able to extract tooth buds from them. They cultured these dental cells, as well as cells from human teeth, in the lab and then added them to a bioengineered scaffold that helped provide the necessary cues to start tooth development. Then they implanted these bioengineered tooth buds into the jaws of adult pigs, and monitored the animals for several months.

The researchers found that the bioengineered teeth developed at a similar rate as natural pig teeth, which is fairly close to that of human teeth. Because the experiment was only planned for three months, the teeth did not have a chance to emerge through the gums, but they underwent the same developmental stages as natural teeth.

“We found that we could make these beautiful little teeth,” Yelick says. “They’re still in the jaw—they haven’t erupted yet—but they look just like natural human teeth.”

Yelick and her colleagues hope to follow the tooth development for a longer duration in future experiments. They are also investigating the signaling molecules that direct cell behavior, looking for ways to initiate tooth growth from within the jaw instead of needing to extract and culture cells separately in the lab.

Their ultimate goal is to be able to prompt cells within a person’s jaw to grow new, entirely human teeth—no pig cells required. There is still more work to be done before the researchers are able to grow a living replacement for a human tooth, but Yelick thinks it is achievable in the next decade.

“Ideally, you keep your teeth as long as possible. That’s the best scenario,” Yelick says. “But if something happens, we hope to have biological tooth substitutes available.”