The dentist's drill is a sound that sends shudders down the spines of many people, so it sure would be nice if teeth could just repair themselves. Thankfully that's not as far-fetched as it sounds – researchers from the University of Plymouth have found a new population of stem cells in mice that are in charge of repairing tooth tissue and could be recruited to help us patch up cavities.

Proper dental care is drilled (pun intended) into kids for a very good reason: our teeth are with us for life. Dentin, a tough tissue that covers the main body of a tooth, is one of the few parts of the human body that can't regenerate naturally, which is what makes tooth decay and injuries such a frustrating problem.

But not all animals are this limited. Many rodents, for example, have incisors (front teeth) that continuously grow over their lifetimes, to the point where they have to constantly gnaw on things to wear them down. The researchers on the new study focused on how these teeth regrow dentin, which we humans can't regenerate.

In the teeth of these mice, the team discovered a new population of mesenchymal stem cells, which are found in muscle and bone. The researchers showed that these cells are responsible for creating new dentin, controlling the number of new cells produced through a molecular gene called Dlk1.

In a further step, the team found that the Dlk1 gene not only plays an important part in the ongoing process of growing tooth tissue, but it does help patch up injuries as well.

"Stem cells are so important, as, in the future, they could be used by laboratories to regenerate tissues that have been damaged or lost due to disease – so it's vital to understand how they work," says Bing Hu, lead researcher on the study. "By uncovering both the new stem cells that make the main body of a tooth and establishing their vital use of Dlk1 in regenerating the tissue, we have taken major steps in understanding stem cell regeneration."

Of course, there's a big asterisk next to this conclusion – human teeth are very different, not least because they don't naturally regenerate. Further work will need to be done to determine if this same gene and stem cells can be manipulated in humans to unlock the ability to regrow dentin.

In the meantime, there are other techniques that may be closer to fruition. Last year, scientists from the University of Pennsylvania used stem cells harvested from patients' baby teeth to repair injuries to permanent teeth. This work was done in humans, so that bridge has already been crossed. Other techniques involve painting peptide-based fluids onto damaged teeth to stimulate them to regenerate, or even using low-powered lasers to coax dental stem cells to form dentin.

The new work was published in the journal Nature Communications.

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