No one likes going to the dentist, but you only get one set of permanent teeth so you need to take care of and preserve them for a lifetime.

That situation may be about to change. New research in Japan has shown regrowing a tooth to replace a missing one may not be that far out in the future.

In humans, teeth are programed during development to a set number. After we lose our baby teeth, we grow 32 teeth as an adult. This includes four wisdom teeth that develop later. Some people don’t have all four wisdom teeth and, in rare cases, some people produce additional teeth, called supernumerary teeth.

Scientists have been looking into the genetic factors and molecular processes required to grow extra teeth. Research teams have found the formation of supernumerary teeth is prevented by a single gene called Usag-1, which stands for uterine sensitization-associated gene-1.

What does a urogenital gene have to do with tooth formation? It has been identified as playing important roles in many tissues, including controlling the growth of teeth.

This gene produces a protein called USAG-1 that inhibits two signaling molecules that are necessary for tooth growth and development. The two signaling molecules are bone morphogenetic protein and Wnt. Signaling molecules are important in development of tissues because they tell the tissue when and how to grow.

So, when USAG-1 is present, these signaling molecules can’t work. Both the signaling molecules are essential for tooth development, so the scientists wanted to know: If USAG-1 is selectively removed and the bone morphogenetic protein signaling molecules become active, will new teeth form?

The research team conducted its experiments using mice and ferrets. It chose ferrets because they have teeth that are more human-like than mice. The scientists developed special biochemical tools called monoclonal antibodies. These antibodies attach to USAG-1 and don’t let it interact with bone morphogenetic protein.

This releases the bone morphogenetic protein to be active, so it can tell the tissues to form supernumerary teeth. The process worked in the test animals, but we’re not out of the woods yet. These molecules play powerful roles in development around the body, so changing the activity of these molecules could have profound impacts that we must test thoroughly.

There are likely ways to apply this treatment to just areas missing teeth. This could be developed as a way to replace teeth lost after childhood or to grow teeth that may not have developed because of a congenital condition.

Dentures and implants could become a thing of the past. Hockey and rugby players can rejoice. And tooth fairies can celebrate — as more teeth are produced, their business will expand.

Medical Discovery News is hosted by professor emeritus Norbert Herzog, and professor David Niesel of the University of Texas Medical Branch. Learn more at

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