Japanese scientists have managed to create teeth from mouse stem cells, and transplant them into the lower jaws of mice, Reuters reports. Entire tooth units (with connective fibres and bone) were attached so that they could chew normally. The teeth were grown from stem cells taken from the mice’s molar teeth, and grown in a mold so they kept the right shape. These took 40 days to fuse with tissues and jaw bones in the mouse who received the transplant. This could be an important step towards growing human organs from a patient’s cells, which could help treat everything from diabetes to spinal cord injuries.