A team from the Forsyth Institute in Boston placed cells from immature teeth of six-month-old pigs in the intestines of rat hosts.

Within 30 weeks small, recognizable tooth crowns had formed, complete with a bone-like layer known as dentin, a well-defined pulp chamber and even enamel.

The study also gave evidence of the existence of dental stem cells which could be the key to implementing such techniques with human teeth.

Stem cells, found in both embryos and adults, produce other cells from tissue to bone to blood.

"The ability to identify, isolate and propagate dental stem cells to use in biological replacement tooth therapy has the potential to revolutionize dentistry," said Dominick DePaola, president of the Forsyth Institute.

Pamela Yelick one of the team members predicted within five years "we will know whether dental stem cells can be manipulated to bioengineer teeth. To generate a human tooth might take an additional five to 10 years."

Details of the study are to be published in the October 1 edition of the Journal of Dental Research.

In the United States, adults over the age of 50 have lost an average of 12 teeth, including their four wisdom teeth, according to a 2000 report by the US Surgeon General.

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