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Growing Teeth with Stem Cell Technology
davidoff404 writes "Lost a tooth lately? Well, a natural cure may be at hand. The BBC is reporting on a grant awarded to researchers at King's College, London, which they say will allow them to develop a technique for growing natural replacement teeth. Using recently developed techniques, stem cells can be programmed to develop into teeth, and then inserted into the gap in a patient's jaw. According to the BBC, the research has already been successfully performed on mice, and clinical trials on humans should begin within two years."
While the growing of teeth is certainly an interesting and useful application of this technology, I personally would like to see how they handle connecting the nerves in the new teeth to the roots in the host.
Depending on how it's handled, it could possibly be applied to a number of other useful medical advances, such as helping repair nerve damage, prosthetic limbs, and spinal cord injuries.
Aren't stem cells wonderful things?
Fetal stem cell research is almost irrelevant. The Australians have extracted stem cells from baby teeth. It gives new meaning to why the tooth fairy leaves money. Then there is the process for extracting stem cells from body fat. Stem cell research does not need to be used as a reason for killing off unwanted pregnancies. Fetus's are not the only source of stem cells, they are just one of the first sources discovered.
"I went on a diet, swore off drinking and heavy eating. And in fourteen days, I had lost exactly two weeks. Joe E. Lewis
I had a class in comparative vertebrate morphology last term, and we talked about this very issue. Highly innnervated teeth is a mammalian trait. Other vertebrates (reptiles, amphibians, birds, fish, etc.) don't have a lot of nerves in their teeth. As you probably know, mammals have only two sets of teeth: the milk (or "baby") teeth and the adult teeth. The milk teeth fall out and are replaced during childhood/adolscence. Other vertebrates typically grow replacement teeth throughout their lives.
Why is this the case? Mammals process their food with their teeth much more than other vertebrates do. This allows us to eat more difficult things like tough plant parts and insects with hard exoskeletons that are unavailable as a food source to other vertebrates. This is one of the keys to mammalian success.
Mastication requires precise occlusion of the upper and lower teeth. Mammalian teeth have highly specialized forms for grinding, shearing, tearing, etc., and different regions of the jaw have different shapes of teeth. This precise occlusion is hard to maintain if teeth are constantly being lost and regrown, so mammals compromised: In exchange for really excellent, highly specialized teeth that allow them to exploit otherwise unavailable food resources, they only have two sets of teeth for their entire lives.
Here's a geek analogy: you have a certain amount of money you can spend on a new computer. Do you spend the big bucks and get a really great piece of hardware (like a G5 PowerMac or something) or do you buy rubbish and get two of them? Mammals decided to spend the big bucks and buy quality. Judging by the success of mammals, I'd say they made a good decision.
Having such awesome, precious teeth, mammals must protect them. The muscles of the jaw are easily strong enough to crush your teeth into powder. Having lots of nerves in teeth is one way that mammals prevent their teeth from premature destruction.
So how did mammals get away with only having two sets of teeth? Two ideas: 1) selection is weaker on older organisms that have already reproduced. Problems related to teeth wearing out are generally found among older individuals. 2) Primitive mammals were typically small (like the size of most rodents). Body size is positively correlated with lifespan in mammals, so the early mammals probably idn't live to be very old. Perhaps they didn't live long enough to wear out their teeth. By the time larger mammals evolved the dentition system was sort of set in stone, and they had to make do in other ways (and there are some amazing adaptations found among mammals for preserving their adult teeth as long as possible).