You really don't want a root canal, and not just because it's potentially painful. Emptying the tooth of the infected tissue at its heart potentially weakens it, since you can't grow that organic material back or put toxic fillings in its place. Researchers may have a solution, though. They've crafted fillings that get the tooth's own stem cells to regenerate and repair tissue. This doesn't mean that your pearly whites would return to normal, but the substance could heal the tooth enough to spare you a root canal or prevent fillings from going south.