Many religious groups object to using embryos for medical research
Japanese scientists say they have created human stem cells from tissue taken from the discarded wisdom teeth of a 10-year-old girl.
The researchers say their work suggests that wisdom teeth could be a suitable alternative to human embryos as a source for therapeutic stem cells.
Research involving stem cells is seen as having the potential to treat many life-threatening diseases.
But some people do not believe it is morally right to use human embryos.
The researchers, based at the National Institute of Advanced Industrial Science and Technology (AIST), say it will be at least five years before their findings result in practical medical applications.
Stem cells have the ability to develop into other kinds of human cells, and experts believe they may eventually lead to treatments for some of the most intractable conditions, such as cancer and diabetes.
The AIST researchers said they had identified a form of stem cell in the wisdom teeth which had the capability to develop and be grown successfully into other forms of cell outside the body.
The cells they harvested continued to grow in the laboratory for just over a month, they added.
The leader of the team, Hajime Ogushi, said the research was significant in two ways.
"One is that we can avoid the ethical issues of stem cells because wisdom teeth are destined to be thrown away anyway," he told the AFP news agency.
"Also, we used teeth that had been extracted three years ago and had been preserved in a freezer. That means that it's easy for us to stock this source of stem cells."
In the US, dentists are starting to offer to store stem cells taken from wisdom teeth and from baby teeth, another potential source, for therapeutic purposes in the future.
Last year, a team of US and Japanese scientists announced they had managed to produce stem cells from skin.