Teaching Our Teeth to Heal Themselves

(Credit: kurhan/Shutterstock) Instead of filling our cavity-ridden teeth with putties and cements, a new method that kicks stem cells into action could help teeth repair themselves. Researchers from King's College London implanted collagen sponges soaked with three inhibitor,s including a drug which has been tested as a therapeutic for Alzheimer's, in damaged mouse teeth. Once in place, the drug-infused sponges catalyzed stem cells inside of the dentin — the bony material beneath hard enamel — filling cavities with living tissue and restoring that part of the tooth to health. 

The researchers drilled holes in the mice's teeth and then filled them in with sponges soaked in one of three types of glycogen synthase kinase inhibitors (GSK-3). One of the three inhibitors, called Tideglusib, has been tested as a treatment for Alzheimer's: GSK-3 inhibitors are thought to reduce the number of beta-amyloid plaques and tau proteins in the brain. When you add GSK-3 inhibitors to the dentin, it appears to signal mesenchymal stem cells there to form new cells and regenerate dentin. Our teeth produce enough dentin on their own to repair small cracks and injuries, but when a larger cavity necessitates drilling, our teeth aren't up to the job. Dentists usually fill in the hole with cements and putties that seal the gap, but these artificial implants can deteriorate over time and fall off. Filling in a cavity with real tooth material is far preferable, not only because it lasts longer, but because a whole tooth is also much healthier. “The tooth is not just a lump of mineral, it’s got its own physiology. You’re replacing a living tissue with an inert cement,” said Paul Sharpe, lead author of the study, speaking to The Guardian. “Fillings work fine, but if the tooth can repair itself, surely [that’s] the best way. You’re restoring all the vitality of the tooth.”

The researchers examined the mice teeth six weeks after the sponges were inserted. The sponges were gone, and in their place was new, healthy dentin. They published their work Monday in Scientific Reports. Of the three GSK-3 inhibitors, Tideglusib has already been tested for safety in humans, making it an appealing option for future applications in human teeth. The amount of the drug they used in their experiment was far less than that used by Alzheimer's researchers, meaning the odds of any ill effects are quite low. The King's College researchers aren't the first to use dental stem cells to kickstart healing in teeth. In June of last year, researchers from the University of Nottingham and the Wyss Institute at Harvard won a prize from the Royal Chemistry Society for a similar approach.While the specific details of their work aren't available yet, it seems that they used a synthetic material to spur the growth of dental stem cells and create dentin.

Dental stem cells could be used for more than just creating dentin. There has been interest in using the cells to grow whole teeth, and the range of applications could extend to other parts of the body as well. Mesenchymal stem cells, of the kind found in the tooth, can form bone, cartilage, muscle and fat cells in addition to the odontoblasts they create in teeth. Further, dental stem cells can be extracted with a safe, minimally invasive procedure. For now, the researchers are expanding their study to rats — they have larger teeth — to see how well the collagen sponges hold up in their cavities. If that goes well, they hope to begin testing the procedure in humans. Someday soon, we might fill the largest cavities with the tooth, the whole tooth, and nothing but the tooth.