Replacing missing teeth with new bioengineered teeth, grown from stem cells generated from a person's own gum cells, is a future method that could be superior to the currently used implant technology, but for now not all required pieces are in place.

New research, published in the Journal of Dental Research and led by Professor Paul Sharpe, an expert in craniofacial development and stem cell biology at King's College London's Dental Institute, describes an important preliminary step towards the development of this method by sourcing the required cells from a patient's own gum.

Research towards producing bioengineered teeth, also called bioteeth, aims to grow new and natural teeth by employing stem cell technology which generates immature teeth (teeth primordia) that mimic those in the embryo. These can be transplanted as small cell pellets into the adult jaw to develop into functional teeth, given the right circumstances, programming and assembly -- all of that difficult to master and not even tested yet -- the researchers say.

Remarkably, despite the very different environments, embryonic teeth primordia were found to develop normally in the adult mouth. Embryonic tooth primordia cells can readily form immature teeth following dissociation into single cell populations and subsequent recombination, but until now the available sources of these cells were impractical to use in a general therapy.

"What is required is the identification of adult sources of human epithelial and mesenchymal [stem] cells that can be obtained in sufficient numbers to make biotooth formation a viable alternative to dental implants," said Sharpe.

This challenge was now solved by the researchers, who successfully isolated adult human gum (gingival) tissue from patients at the Dental Institute at King's College London and used this to get epithlial stem cells, also grewing more of it in the lab. These adult stem cells could then be combined with the embryonic stem cells of mice that form teeth -- called mesenchyme cells, and not yet available as human adult stem cells. By transplanting this combination of cells into mice, the researchers were able to grow hybrid human/mouse teeth containing dentine and enamel, as well as viable roots.

"Epithelial cells derived from adult human gum tissue are capable of responding to tooth inducing signals from embryonic tooth mesenchyme in an appropriate way to contribute to tooth crown and root formation and give rise to relevant differentiated cell types, following in vitro culture," explained Sharpe.

"These easily accessible epithelial cells are thus a realistic source for consideration in human biotooth formation. 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."

Current implant-based methods of whole tooth replacement can occasionally cause problems as the natural root structure cannot be reproduced and as a consequence of the friction from eating and other jaw movement, loss of jaw bone can gradually occur around the implant.

Paper:

A. Angelova Volponi, M. Kawasaki, P. T. Sharpe, Adult Human Gingival Epithelial Cells as a Source for Whole-tooth Bioengineering, Journal of Dental Research, 2013, DOI: 10.1177/0022034513481041



