A healthy tooth has dental pulp at its core. That pulp, which contains nerves and blood vessels, is surrounded by layers of hard tissues called dentin, cementum, and enamel. These layers are extraordinarily tough—enamel is considered the hardest tissue in the body—but they can be eroded by bacteria, resulting in tooth decay. And if that decay reaches the dental pulp, it can hurt. A lot.
Dentists can remove areas of decay and replace them with fillings, which typically last for up to around 15 years. But then they need to be replaced, and each time that happens, more of the tooth has to be cut away. “Eventually … it’s almost inevitable that the person is going to lose that tooth,” says França.
Today, someone who loses a tooth might opt to replace it with a dental implant. These implants consist of a titanium screw anchored into the jawbone and typically topped with a toothlike porcelain crown. They look like teeth and can be used to bite and chew food, but they fall far short of the real thing.
If the implant is not perfectly aligned with a person’s existing teeth, biting and chewing can transmit uneven forces to the surrounding jawbone, damaging the bone that supports it, says Yelick. Bacteria can attach to the implants, sometimes causing an infection called peri-implantitis, which can lead to bone loss.
“It’s very difficult to replace an implant, because first you have to rebuild all the bone that has been absorbed over time that’s gone away,” says Yelick. For the last few decades, she’s been working to create more humanlike tooth substitutes, using cells taken from real teeth and grown in the lab into toothlike structures. “We’re working on trying to create functional replacement teeth,” she says.
For her research, Yelick uses cells from pig jaws, which she obtains from slaughterhouses. Pigs grow multiple sets of teeth throughout their lives, so the jawbones contain cells from underdeveloped teeth that have not yet broken through the gums. Yelick and Zhang collect cells from these teeth and coax them in the lab to grow and multiply until they have “tens of millions” of cells.
In previous experiments, Yelick and other colleagues have seeded these cells onto “scaffolds”—biodegradable tooth-shaped structures—and implanted them into rats. Rats have small jaws, so they inserted the scaffolds under the skin on the animals’ abdomens. “It doesn’t bother the rats,” says Yelick.
#Humanlike #teeth #grown #mini #pigs
