A team of Japanese scientists have created complete tooth units by using mouse stem cells and successfully transplanted them into mice. The tooth units, which also contain connective fibers and bones, were attached successfully to the lower jaw bones, and helped the rats to chew normally, researchers wrote in PLoS One. As the first step, researchers isolated two types of stem cells from the molar teeth of mice and grew them in the laboratory. The cells formed a tiny "tooth bud" within five days, which were then placed in a mold. The primary structures were then placed inside the body of the mouse until a complete tooth unit was formed. "The bioengineered teeth were fully functional ... there was no trouble (with) biting and eating food after transplantation," wrote Masamitsu Oshima from the Research Institute for Science and Technology, Tokyo University of Science. Researchers have expressed hope that their proceeding would pave the way for the development of functional human organs including teeth from a patient's own cells, Reuters reported. "At present, researchers worldwide do not have the method to culture three-dimensional organs in vitro (outside the body)," said lead author Professor Takashi Tsuji. "It is important to develop technologies for the culture of the bioengineered organ ... for the realization of future organ replacement regenerative therapy," he added.