Dentists may one day be able to replace missing teeth with ones newly grown from gum cells, say UK researchers.
The team from King's College London took cells from adult human gum tissue and combined them with another type of cell from mice to grow a tooth.
They say using a readily available source of cells pushes the technology a step nearer to being available to patients.
But it is still likely to be many years before dentists can use the method.
Other work has focused on using embryonic stem cells to create "bioteeth".
It proved it could be done but is expensive and impractical for use in the clinic, the researchers said.
In the latest study they took human epithelial cells from the gums of human patients, grew more of them in the lab and mixed them with mesenchyme cells from mice.
The mesenchyme cells were cultured to be "inducing" - they instruct the epithelial cells to start growing into a tooth.
Transplanting the cell combination into mice, researchers were able to grow hybrid human/mouse teeth that had viable roots, they reported in the Journal of Dental Research.
It has already been shown that small pellets of the right type of cells transplanted into the jaw can develop into functional teeth.
The next step will be to get an easily accessible source of human mesenchyme cells and grow enough of them for it to be a useful technique in the clinic.
Study leader Prof Paul Sharpe said mesenchyme cells could be found in the pulp of wisdom teeth, among other sources, but the difficulty had been in getting hold of enough of them.
"This advance here is we have identified a cell population you could envisage using in the clinic. We are now working to try and identify a simple way of getting mesenchyme."
He added: "The next major challenge is to identify a way to culture adult human mesenchymal cells to be tooth-inducing, as at the moment we can only make embryonic mesenchymal cells do this."
He said the hope was that one day the technology could replace current dental implants, which cannot reproduce a natural root structure. Also friction from eating and other jaw movement can cause the bone around the implant to wear away.
"But if it's going to work it has to be about the same price as a dental implant so we have to find a way to do it that is easy and cheap."
Prof Alastair Sloan, an expert in bone biology and tissue engineering at Cardiff University, said the work was significant but there remained many hurdles before it would be available to patients.
"They have used cells from the gum and the fact that it is developing a root is an exciting step forward.
"We are still some way from engineering a whole organ like a tooth but the knock-on effect of research like this is developing bio-fillings, so some aspects of the technology are feasible within the next 10 to 15 years."