A Japanese Biotech Company is Advancing Human Trials for a Tooth-Regrowing Drug

For generations, the loss of a permanent tooth has meant relying on artificial substitutes. Whether through titanium implants, porcelain bridges, or removable dentures, modern dentistry has excelled at mimicking natural teeth but has never been able to replace them with living tissue.[3]

That paradigm is now shifting. A Japanese biotechnology company, Toregem BioPharma, is advancing clinical trials for a drug designed to stimulate the human body to grow new, natural teeth.[1]

In June 2026, the Kyoto University spin-out announced it had secured $5.3 million in new funding, bringing its total capital raised to over $29 million. This financial injection is earmarked to accelerate Phase II human clinical trials for the company’s lead candidate, an experimental antibody treatment known as TRG035.[1][3]

The science behind TRG035 hinges on a protein called Uterine Sensitization Associated Gene-1, or USAG-1. In the human body, USAG-1 acts as a biological brake pedal. It interacts with signaling pathways to suppress tooth development, ensuring that humans only grow two sets of teeth: baby teeth and permanent adult teeth.[3][5]

Researchers discovered that by neutralizing this protein, they could release the brake. TRG035 is an intravenously administered antibody that binds to and inhibits USAG-1. By blocking the protein's suppressive effects, the drug activates dormant, vestigial tooth buds that remain hidden inside the human jawline.[2][3][5]

The concept relies on the theory of "third dentition." While humans typically only erupt two sets of teeth, the foundational cellular structures capable of producing a third set remain intact but inactive. TRG035 essentially signals these dormant buds to wake up and begin the growth process.[3][4]

The journey to human trials began with highly successful animal models. In a landmark 2021 study, researchers demonstrated that blocking USAG-1 successfully stimulated tooth regrowth in mice that were genetically engineered to lack teeth.[2][5]

The team subsequently tested the drug on ferrets and dogs, animals with dental structures more closely resembling those of humans. In both cases, the animals successfully grew functional new teeth without exhibiting significant adverse side effects, paving the way for human testing.[5]

Phase I clinical trials commenced in late 2024 at Kyoto University Hospital. The initial study enrolled 30 healthy adult men between the ages of 30 and 64, each missing at least one rear tooth. Because the primary goal of Phase I testing is to evaluate safety and dosage rather than efficacy, researchers closely monitored the participants for adverse reactions.[4][5]

Preliminary results from the Phase I trials have been highly encouraging. The initial cohort of volunteers completed the testing without any serious adverse events being reported, successfully clearing the first major regulatory hurdle for the drug.[3][4]

With safety data in hand, Toregem is now pivoting to Phase II, which will focus on the demographic that stands to benefit most immediately: children suffering from severe congenital hypodontia.[3]

Congenital hypodontia is a rare genetic condition in which patients are born missing six or more permanent teeth. For these children, the clinical stakes are incredibly high. Because their jawbones are still growing and developing, traditional dental implants cannot be safely anchored into the bone.[1][3]

As a result, pediatric patients with severe hypodontia are often forced to rely on removable dentures for years until they reach adulthood. This prolonged wait can severely impact their ability to chew, speak properly, and develop normal facial structures, while also taking a psychological toll.[3][4]

If TRG035 proves effective in Phase II trials, it could offer a biological cure for these children, allowing them to grow their own missing teeth naturally and bypass years of invasive and imperfect artificial interventions.[1][4]

While the immediate focus remains on congenital conditions, the long-term vision for TRG035 is far broader. Toregem ultimately hopes to adapt the treatment for adults who have lost teeth due to severe decay, periodontal disease, or physical trauma.[1][3]

However, experts caution that significant hurdles remain before tooth-regrowing injections become a routine part of dental care. One major challenge is ensuring that a newly stimulated tooth grows in the correct alignment and successfully integrates with the jaw's existing network of nerves and blood vessels.[2]

There are also questions regarding the precision of the drug. Because the treatment is administered systemically via an intravenous injection, researchers must ensure that the antibody only triggers growth in the specific areas where teeth are missing, rather than causing unwanted tooth development across the entire jaw.[2]

Cost is another factor that will need to be addressed. Early estimates suggest that, if approved, the initial price of the treatment could be substantial, potentially limiting access until manufacturing scales and insurance frameworks adapt to the new technology.[5]

Despite these challenges, the dental and medical communities are watching the Kyoto trials with intense interest. Toregem has stated a provisional goal of bringing the drug to the commercial market by 2030, pending successful efficacy data and regulatory approvals.[2][5]

If that timeline holds, the end of the decade could witness one of the most profound medical breakthroughs of the century: the ability to harness the body's own biology to replace what was once thought permanently lost.[2][4]