People with missing teeth could grow new ones, say Japanese dentists testing a pioneering drug they hope they will offer an alternative to dentures and implants.
Unlike reptiles and fish, which typically replace their fangs regularly, it is widely accepted that humans and most other mammals have only two sets of teeth.
But hidden beneath our gums are the dormant buds of a third generation, according to Katsu Takahashi, head of the oral surgery department at Osaka Medical Research Institute’s Kitano Hospital.
His team launched clinical trials at Kyoto University Hospital in October, giving adult subjects an experimental drug that they say has the potential to restart the growth of those hidden teeth.
This is a “completely new” technology for the world, Takahashi told AFP.
Prosthetic treatments used for teeth lost due to decay, disease or injury are often considered expensive and invasive.
“So there are certainly benefits to restoring natural teeth,” said Takahashi, the project’s lead researcher.
Tests on mice and ferrets suggest that blocking a protein called USAG-1 can awaken the third set, and researchers have published laboratory photographs of regrown animal teeth.
In a study published last yearthe team declared its ” antibody treatment in mice is effective for tooth regeneration and may represent a major advance in the treatment of dental abnormalities in humans.”
Only the beginning
For now, dentists are prioritizing the “urgent” needs of patients missing six or more permanent teeth since birth.
This hereditary condition is said to affect around 0.1% of people, who may have severe difficulty chewing, and in Japan they often spend most of their teenage years wearing a face mask to hide the wide openings in their mouths , Takahashi said.
“This drug could be a game-changer for them,” he added.
The drug is therefore primarily aimed at children and researchers want to make it available by 2030.
Angray Kang, professor of dentistry at Queen Mary University of London, knows of only one other team pursuing a similar goal of using antibody to regrow or repair teeth.
“I would say that the Takahashi group is showing the way,” this immunotechnology expert, who is not linked to Japanese research, told AFP.
Takahashi’s work is “exciting and worth pursuing,” Kang said, in part because an antibody targeting a protein almost identical to USAG-1 is already used to treat osteoporosis.
“The race to regenerate human teeth is not a short sprint, but by analogy a series of consecutive ultra-marathons,” he said.
“This is just the beginning.”
Chengfei Zhang, clinical professor of endodontics at the University of Hong Kong, said Takahashi’s method is “innovative and has potential.”
“The claim that humans have latent tooth buds capable of producing a third set of teeth is both revolutionary and controversial,” he told AFP.
He also cautioned that “results observed in animals do not always translate directly to humans.”
The results of the animal experiments raise “questions about whether regenerated teeth could functionally and aesthetically replace missing teeth,” Zhang added.
Above the Moon
A confident Takahashi says the location of a new tooth in a mouth can be controlled, or even localized, by the drug injection site.
And if it grows in the wrong place, it can be moved through orthodontics or a transplant, he said.
No young patients with congenital diseases participate in the first clinical trialbecause the main goal is to test the safety of the drug rather than its effectiveness.
So for now, participants are healthy adults who have lost at least one existing tooth.
And even if tooth regeneration isn’t the express goal of the trial this time, there’s a small chance it could happen to the subjects anyway, Takahashi said.
If so, researchers will have confirmed that the drug can be effective for edentulous people – which would be a medical triumph.
“I would be done the Moon if that happens,” Takahashi said.
This could be particularly welcome news in Japan, which has the second oldest population in the world.
Health Ministry data shows that more than 90% of people aged 75 or older in Japan are missing at least one tooth.
“There is great expectation that our technology can directly extend their healthy life expectancy,” Takahashi said.