Somebody Is Trying to Make Humans Grow a Third Set

The single most upvoted thing anyone says about losing teeth:

Full dentures are hell, keep as many teeth as possible, cant go back from that except with implants r/askdentists

Can’t go back. That’s the assumption everything in dentistry is built on. And a lab in Kyoto is currently testing whether it’s true.

Your body may have spare teeth in it

Humans get two sets. Some animals get an endless supply — sharks, crocodiles, most reptiles — replacing teeth their whole lives.

The interesting part is that the genetic machinery for making a tooth didn’t disappear from us. It’s still there. It just gets switched off after the second set, and there is evidence that some people carry dormant buds for a third one that never develops. Occasionally one slips through:

I actually had one wisdom tooth grow back soooo I guess it’s possible! r/Mommit

So the question researchers asked wasn’t how do we build a tooth. It was what is holding the off switch down.

The protein with the off switch

The answer they landed on is a protein called USAG-1. Its job is to suppress tooth development — it sits on the signals that would otherwise tell a bud to grow.

Block it, and the brakes come off. Mice bred without USAG-1 grow extra teeth. Give normal mice an antibody that neutralises it, and they grow extra teeth too. Same result in ferrets, whose teeth are much more like ours.

That work turned into a drug: an antibody now called TRG035, from Toregem BioPharma, a spin-out from Kyoto University.

Where it actually is right now

This is the part usually missing from the headlines, so plainly:

A first human trial has been done. Adults missing at least one tooth, testing safety rather than whether anything grows. It finished without serious adverse events. Final results are still pending.

The next stage is funded. In May 2026 the company announced financing to run a second-stage trial in Japan and to prepare for development in the United States.

The target group is specific. That next trial is aimed at people with severe congenital tooth agenesis — born missing six or more permanent teeth. Not people who lost a molar to a cavity.

The team has talked about general use around 2030. Drug timelines slip. Treat that as a hope.

Why it matters even if it’s years away

Look at what the current menu actually is:

Veneers won’t replace missing teeth. Your options are a bridge, implants, or dentures r/askdentists

Veneers make existing teeth look nice but they can’t be used to replace missing teeth. To replace teeth you’ll need a bridge, implants, or dentures. r/askdentists

Bridge, implant, denture. Every one of those is a replacement — titanium, ceramic, acrylic. Impressive engineering, none of it a tooth. None of it has a living root, a ligament, or a nerve that tells you how hard you’re biting.

And the whole field has operated under one closed door:

Since you can’t grow wisdom teeth back r/Mommit

That sentence has been true for the entire history of medicine. It’s now, for the first time, an open research question.

The short version

There is a drug. It is real, it has been in humans, and it is aimed first at people who were born without teeth.

Nobody is growing you a new molar this decade. But the sentence you can’t grow teeth back has quietly stopped being a fact and started being a deadline.