Every time a child loses a baby tooth and a permanent tooth grows in its place, it seems natural to us. But when an adult loses a permanent tooth, the need for an implant has always been a "sentence." The biological reason for this difference is not that we lack the infrastructure—we have it. Deep in the jaw, beneath the permanent teeth, most humans carry dormant genes for "third teeth" that have never been activated. Until now.
The Japanese company Toregem Biopharma, a spin-off of Kyoto University Hospital, has completed all regulatory preparations and began this week the world's first clinical trial in humans of a drug that will activate these genes and cause a new tooth to grow fully biologically.
The Story of USAG-1
The team led by Prof. Katsuo Takahashi researched for 20 years why genes for additional teeth remain dormant. They identified a protein called USAG-1 (Uterine Sensitization-Associated Gene-1) that functions as a "cancel switch"—it blocks the signals that allow third tooth genes to express.
The rationale is clear: if we can block the blocker, the natural signals for tooth growth can work again.
The Animal Trial: Results That Led to the Clinic
In preclinical studies published in recent years, the team showed that:
- In mice engineered without molars: a single injection of anti-USAG-1 antibody caused completely normal teeth to grow within 3 months.
- In French bulldogs (which have congenital dental problems): the trial also succeeded in them—new teeth grew in the correct places, with roots, enamel, and pulp.
- In healthy animals: the treatment caused "additional teeth" to grow from dormant genes, proving the mechanism works even without prior genetic engineering.
The Clinical Trial: Phase 1
The trial that began this month includes:
- 30 participants, ages 30-60.
- Patients who have lost at least one tooth for reasons other than accident (periodontal degeneration, severe caries, etc.).
- A single dose of the antibody via IV injection.
- Follow-up period: 12 months, with CT scans and periodic dental exams.
The primary goal in this phase is safety—to ensure no side effects. The secondary goal: to identify initial signs of new tooth growth. Preliminary results are expected in 2027.
If It Works...
The potential implications are enormous:
- The end of the implant era? If one procedure can restore a biological tooth instead of a titanium screw, there is no reason to continue with implants. A living biological tooth for life, connected to the nerve, sensing pressure.
- A solution for congenital anodontia: 1% of the population is born missing some teeth. They would be the first to benefit.
- Potentially low cost: After standardization, the antibody may be cheaper than a quality implant.
- Growth time: A tooth in children develops over about 6-12 months. Likely similar here—not an immediate result, but maximal.
The Risks and Open Questions
Even the researchers are cautious. Several legitimate concerns:
- Unwanted teeth: If the mechanism activates excessively, a patient could develop additional teeth in wrong places. The question is how to "direct" the growth.
- Systemic effects: USAG-1 is also active in the kidney, blood vessels, and other organs. A systemic antibody could cause side effects in these systems.
- Older ages: It is not yet clear if patients over 70 will retain enough local stem cells in the jaw to support growth.
- Tooth quality: Even in mice, the growing teeth were not always perfect in size and shape.
Why Japan?
Three main reasons:
- Japanese lead in stem cell research—since Shinya Yamanaka won the Nobel in 2012, Japan has invested heavily in the field.
- Faster regulatory approval—Japanese PMDA laws tend to approve regenerative treatments faster than the American FDA.
- An aging population—Japan is the country with the highest percentage of elderly in the world, creating political demand for innovative anti-aging treatments.
What This Means for You
If you have lost a tooth or expect to lose one in the near future—do not stop your standard treatment for this trial. Even in the best case, the drug will be commercially available only by 2030 at the earliest, and years later outside Japan. A quality implant performed today is still the best solution.
But if you are very young and have decades ahead, or if you know you will lose teeth in the near future (advanced periodontal degeneration, for example)—it is worth starting to follow the news from Toregem. We may be less than a decade away from an era where dentistry will be biological, not mechanical.
References:
Toregem Biopharma
The Economic Times - Tooth Regeneration Article
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