Sharks are experts at growing new teeth from stem cells.
What if we humans could grow new teeth from stem cells too? It seems like a stretch. Compared to sharks, on tooth regrowth we are biological amateurs.
While humans and some other animals like dogs have only two sets of teeth in our whole lives, alligators and sharks have a limitless ability to replace lost teeth with new ones. The key is tooth stem cells.
Learning from sharks on teeth
Over millions of years, billions of sharks have been losing teeth and regrowing new ones such that the bottom of the ocean likely has trillions of shark teeth (or their fossils) in various layers of sediment. One back-of-napkin calculation estimates that over 100 billion sharks have lived on Earth over 100s of millions of years. Long-lived sharks may go through thousands of teeth.
How do they keep making teeth throughout their lifetimes? Can we learn from it?
Sharks replace teeth by growing new ones from stem cells present in the mouth. In theory we could do that too but not quite the same way.
First, researchers have to learn more about shark and alligator process. Then we need to develop the replacement technology. Also, could we potentially fix (rather than replace) broken or diseased teeth too via stem cells? This kind of thing would be a very beneficial form of regenerative medicine.
Humans vs. sharks: new teeth from stem cells
So what do we know about how sharks grow new teeth from stem cells? Researcher Gareth J. Fraser writes that sharks don’t replace lost teeth one by one. Instead, rows of “baby” replacements are present. They can develop into full-grown sets of replacements:
“Sharks don’t actually regrow teeth one by one but have multiple rows inside their jaw that are constantly regrown. When a tooth on the edge of the jaw drops out, the corresponding tooth in the row behind it moves forward to replace it. The underlying soft tissues anchor and carry each tooth like a conveyor belt.”
Tooth stem cells or “dental stem cells” are the key. Fraser with his colleagues Moya Smith and Thimios Mitsiadis define them as “odontogenic stem cells” in their 2009 paper on shark teeth growth. Thus, in principle we humans could regrow new teeth from our own stem cells too. Perhaps even just one-by-one rather than as rows.
Since that paper there’s been much more research in this area that is somewhat encouraging. Note that some folks are also excited about the potential of stem cells isolated from teeth to be used for non-dental applications too. So far, the potential of tooth stem cells, which seem related to mesenchymal cells or MSCs, to make other tissues remains unclear.
Fraser’s team just published a newer paper on the development, regeneration, and evolution of shark teeth that’s also interesting.
Research on growing new teeth from stem cells
A recent article in Science Translation Medicine just a couple of months back from a team in China and at U. Penn suggests that regrowth of teeth or of some components of damaged teeth including in humans via stem cells may be possible in the not-so-distant future. Here’s a brief summary:
“Dental pulp necrosis is one of the most common pathological conditions that results in tooth loss. However, regeneration of functional dental pulp has proved difficult. In a new study, Xuan et al. implanted ex vivo expanded autologous tooth stem cells from deciduous teeth in two animal models and in human patients. They demonstrated regeneration of dental pulp containing an odontoblast layer, blood vessels, and nerves in the implanted teeth and rescue of sensation to stimuli such as temperature. This work suggests that implantation of tooth stem cells can provide partial recovery of teeth injured by trauma.”
When trying to grow a whole new tooth it needs to end up the right size and shape, which are difficult challenges. You also need living tooth roots.
Looking ahead
A PubMed search in 2025 finds a few hundred articles with teeth and stem cells in the title. You can do the search with other similar terms and find a few more articles. Surprisingly, not that many articles focus on using stem cells for tooth replacement.
One key question is whether it is better to grow the teeth in situ in the mouth (like where an old tooth use to be) or bioengineer the new teeth in the lab and then insert them. Another option highlighted by recent research is to grow the human teeth in animals like pigs and then transplant them into people.
Our jaws are very different than sharks so that once we are adults it’s more difficult to imagine growing a new tooth in place.
Overall, this is a promising area of regenerative medicine based on probably primarily adult stem cells. It’s also possible pluripotent stem cells could be used to grow teeth.