20,000 teeth in a lifetime: Scientists are working to regrow human teeth. One creature can already do so

Human teeth cannot grow back. Once you lose a tooth, a new one can either be implanted, or you can leave a hole in your mouth. However, that can change in the coming years. Scientists in Japan are working on an experimental drug that can grow back teeth, and it is already in the human trial phase.

They have figured out that an antibody named Uterine sensitisation–associated gene-1 (USAG-1) stops teeth from growing in ferrets and mice. In 2021, scientists from the Kyoto University, discovered a monoclonal antibody (a technique usually used in fighting cancer) that can stop the USAG-1 from interacting with molecules known as bone morphogenetic protein, or BMP.

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Now they knew that "suppressing USAG-1 benefits tooth growth", but, "What we did not know was whether it would be enough,” Kyoto University’s Katsu Takahashi, a co-author of the study, said in a press statement.

Human trial of teeth-growing medicine

The human trial started last year and will last 11 months. It involves 30 males between the ages of 30 and 64 who will be administered the drug intravenously to check if it works and its safety. There have been no reports of side effects in previous animal studies.

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If the human trials prove successful, the drug will be given to children (2-7 years old) who are missing at least four teeth. Scientists are hoping to make the tooth-growing medicine available by 2030. Initially, only people with congenital tooth deficiency will be the patients to get it. However, later it should be able to help others who have lost a tooth.

“The idea of growing new teeth is every dentist’s dream. I’ve been working on this since I was a graduate student. I was confident I’d be able to make it happen,” Takahashi told Mainichi. “We’re hoping to see a time when tooth regrowth medicine is a third choice alongside dentures and implants.”

Humans have a third set of teeth

In an earlier research, Takahashi discovered that humans have a third set of teeth, which are present but not visible. They sprout up in about one per cent of humans with hyperdontia, where more than a full set of teeth is present. Takahashi focused on this third set and believes the right gene manipulation could promote tooth regrowth.

Which animals can regrow teeth?

There are some creatures that see tooth regrowth. Sharks are one such group of animals that can regrow their teeth. While human teeth are linked to the jawbone, shark teeth are not. So, despite falling out constantly, sharks are never without teeth. The shark's jaw always has new teeth being created, which move forward once the front teeth go bad. Because of this speciality, sharks can have as many as 20,000 teeth in a lifetime.