A groundbreaking shift in dental care may be on the horizon as Japan nears the completion of a human clinical trial for a drug designed to stimulate the regrowth of teeth, set to conclude this August.

Humans, being diphyodonts, naturally grow only two sets of teeth in a lifetime. The first set consists of 20 primary teeth that appear in early childhood and are later replaced by up to 32 permanent teeth beginning around age six. Once lost, permanent teeth do not regenerate.

Researchers in Japan, however, are testing a drug that could make a third set of teeth possible within the next decade.

The ongoing trial, conducted under the Kitano Hospital Medical Research Institute in Osaka with clinical testing at Kyoto University Hospital, began in September–October 2024 and runs for 11 months. It involves 30 men aged 30 to 64 who are each missing at least one permanent molar. The drug is being administered through intravenous (IV) injection.

The experimental medicine targets uterine sensitization–associated gene-1 (USAG-1), a protein that suppresses tooth development. By inhibiting USAG-1 and influencing bone morphogenetic protein (BMP) signaling, the growth of new teeth may be stimulated.

Lead researcher Dr. Katsu Takahashi explained that previous studies suggest a “third set” of teeth already exists in the human mouth, waiting to be activated.

The approach was first found effective with no notable side effects in ferrets and mice, which have dental structures similar to humans.

If successful, the next phase of trials will include children aged two to seven who are missing at least four teeth. Researchers are also targeting general availability by 2030.