Towards Regenerative Medicine for Teeth

This popular science article surveys the present state of development towards the goal of regenerating teeth and their supporting structures. In animal studies, researchers have managed to grow and implant whole teeth, though much work remains to better control the processes involved. Similarly, proof of concept studies have demonstrated regrowth of enamel to heal cavities. More advanced is regeneration of dental pulp, where the established techniques of regenerative medicine and tissue engineering can be applied to the problem directly.

Teeth can undergo a lot of damage. In particular, when wily bacteria sneak past the protective outer layer of the tooth, they can penetrate the dental pulp that lives at its core. These unwanted residents trigger inflammation - more recognizable to us as searing pain and swelling. The teeth aren't defenseless, though. They can fight off minor infections and repair some damage. This ability to regenerate comes from stem cells buried in the dental pulp. These cells can turn into many of the different cell types required for healthy dental pulp, but they don't always have enough juice on their own to restore tissue damaged by an infection or other injury.

One way that scientists imagine repairing a damaged tooth is by delivering stem cells into the tooth and giving them the right signals to regenerate the damaged cells. The tricky part is knowing exactly which factors will lead to this outcome; after all, growing a glob of fat in a tooth socket would not be helpful. Other groups have developed 3D-printed scaffolds designed to match the shape of the damaged area. A team made scaffolds shaped like human and rat teeth out of biodegradable polymers. The scaffolds had tiny channels to deliver molecules that would steer the stem cells toward bone- and tooth-supporting cell types. After nine weeks implanted in a rat, the desired cells began to form at the base of the scaffold.

The ultimate goal for many regenerative dentists is to grow a whole human tooth for implant. However, that possibility is still far away. Teeth are complex organs, with many different components making up even the smallest incisor: dental pulp, enamel, dentin, and more. During human development, mesenchymal stem cells interact with other types of cells to generate the inner and outer layers of a tooth; this process is still poorly understood, and replicating it artificially is no small task. One challenge that continues to stump the scientists is how to get tissue engineered teeth to grow faster. The teeth still seem to follow their normal biological clocks, so they grow too slowly to make them usable on demand in the clinic.