Although humans can't get new teeth, most mammals can.
Many fish and reptiles can have hundreds, if not thousands, of new teeth. Geckos can grow more than 1,000 new teeth per year.
Because of the evolution of human teeth over 300 million years ago, only two sets of teeth can be grown by humans, adult and baby.
Below is the transcript of the video.
Narrator: Humans need dentists. It's a known fact. The US spent $124 billion in 2017 on dental care. An estimated 90% of Americans have fillings.
This problem is not common in many animals. Because they can regrow their damaged teeth and replace them with new pearly whites.
Wouldn't that be wonderful? This is a good trade-off.
Only a few mammals can regrow their teeth multiple times. This is in contrast to the 50,000 species that are reptiles or fish. For example, geckos will replace 100 teeth every 3-4 months. Geckos live 6-10 years and can grow up to 1,800 to 4,000 new teeth per year. This is due to stem cells, a special type cell found in their gums.
Because stem cells can be transformed into other cells, they are very useful. Stem cells can be used to create new teeth, similar to tooth stem cells. These stem cells are present in humans when they're young. However, once our adult teeth are edentulous, these stem cells become inactive and die.
Let's go back in time to understand why. It was around 320 million years ago that mammals and reptiles separated. Aside from the obvious differences, a third change was the shape of teeth. Reptiles are, for instance, generalists. They eat all animals that they can chew. To prevent prey from getting into their mouths, they required teeth of the same shape and size. Mammals have their own diets. For example, grazers that eat only grass and hunters that eat flesh from their kills. Different shapes and purposes have led to different teeth in mammals. This could explain why mammals are unable to regrow more of their teeth.
Let's suppose you could regrow your teeth multiple times. It is important that the top- and bottoms sets match. They won't be able to grind food as efficiently if they don't match. Although it sounds great in principle, the risk of misalignment with each set of regrown teeth is real. The theory that adult humans cannot regrow their teeth is that it's better for survival to have one set of well-aligned adult teeth.
If you want to regrow a tooth however, there might be a way. Scientists have used drugs and lasers to help mice and rats regrow decayed tissue in their cavities-ridden teeth. The idea is that you can regrow whole teeth if you can regenerate tooth tissue.
Although human testing has not been performed, Keep visiting your dentist. For the moment, at least.
NOTE FROM THE EDITOR: This video was first published March 2019.
