Watch Your Mouth: Need a Tooth? Grow Your Own

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Columbia University's Jeremy Mao has vision for the future of dentistry - that dentures and dental implants will one day be a thing of the past. Already, he has successfully grown a new tooth in the mouth of a rat using its own stem cells. He thinks its possible in humans.

MAO : If you imagine I have a missing molar on the right , I have some CT images taken, sent to a lab. Now in 10 days or a week when I go back to my dentist to have my tooth restored, instead of having a dental implant, the dentist could say we've got a tooth that's made just for you.

As Mao explains the process- a CAT scan of a matching tooth on the opposite side of the mouth is used to build a tooth-shaped scaffold of artificial bone that will eventually become a new tooth. To do this researchers use something called a bio printer.

MAO: A bio printer works almost like your color printer at home. With your color printer at home you are using red, blue, green - different colors of ink and you are printing on a piece of paper. With a bio-printer instead of printing ink its printing biomaterials, and instead of printing on a piece of paper in 2 dimensions this is printing in 3 dimensions.

In other words the bio printer deposits droplets of artificial bone that ultimately creates the perfect tooth shaped scaffold. It's not solid. Instead it's filled with tiny channels and pores that allow blood vessels and the body's own stem cells- the regenerative cells of the body- to enter and re-grow the new tooth.

In order to see if the new tooth would actually grow into the scaffold, Mao removed the teeth of laboratory rats and then replaced them with a scaffold from his bioprinter. After nine weeks, the team had a look and was amazed at what they saw.

MAO: The huge surprise is that the whole tooth was regenerated in the rat lower incisor scaffold- if you look at the images of the paper we released in May you'll see bone regenerated, periodontal ligament regenerated and the whole tooth structure was integrated with the surrounding bone.

But a rat tooth is not a human tooth admits Mao - for one thing, the human tooth is a lot bigger and more complex.

Mao: if you can regenerate a tooth for a rat does not necessarily mean you can regenerate a tooth for a dog or a pig - and a human obviously would be even bigger.

So Mao and his colleagues implanted a second tooth scaffold in the back of the rat's jaw - but this one in the size and shape of a human molar - and that one regenerated too.

The other interesting part of what Mao did was that he didn't have to add any external stem cells at all. Instead he used two different proteins that send out a siren call for the body's own stem cells to come and rebuild the tooth.

MAO: They attract your own stem cells within the body to the location to regenerate tissues.

MAO says the procedure, which has not yet been tested in humans, is the first step in proving that conceptually - it can be done. Not only can human sized teeth be grown, but the materials are commercially available and inexpensive enough to make this appealing as a potential clinical treatment. Ultimately, Mao hopes it will cost a fraction of a dental implant, which can run thousands of dollars.

However, others are more skeptical. Arnold Caplan is a stem cell researcher at Case Western Reserve University. As he points out, what works in animals doesn't always translate into humans - for reasons other than size. For one thing he says that the technique Mao is applying relies on a person's pool of available stem cells - and that that pool drops off dramatically as we age.

CAPLAN: I would suspect that Jeremy Mao, if he tries these tricks in humans, is going to have trouble. Especially if they're over the age of fifty, possibly if they are over the age of 20. Their ability to regenerate is different.

Caplan says if tooth regeneration does eventually work in humans it probably won't be available for decades but he says Mao's success is exciting proof of the promise stem cells may hold for the future of medicine and dentistry.

Gretchen Cuda, 90.3

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