Rodent incensors never stop growing. That’s one of the reasons why mice gnaw through cupboards, hamsters chomp cage bars, and rats will chew through just about anything. They need to wear down those incisors, which, if left unchecked, could go so long that the animal might starve.
This feature of rodent dental anatomy gives researchers insight into how to regenerate human teeth, which could change the way dental restorations—crowns, bridges, and “fillings”—are handled in the dental office.
In the study to be published in Development Cell, the research team compares the cells that become mouse incisors with those that become molars, which, as in humans, stop developing after crown formation.
“The major idea of the paper focused on how incisors and molars start with similar developmental processes but differ in tissue homeostasis due to the differing fates of their dental epithelial stem cells,” says Weston Grimes, one of two dental students involved in the study along with Hoang Anh Ho.
It’s these different stem cell fates that leave incisors with a bustling population of epithelial and mesenchymal stem cells to keep them growing throughout life while the stem-cell population of molars lies dormant, according to the article.
“If we can someday use this knowledge to reactivate those stem cells, then we could regrow part of the root,” says study leader Yang Chai, associate dean of research and chair in craniofacial molecular biology at USC’s Herman Ostrow School of Dentistry.
The key, though, is determining how to reactivate those stem cells by manipulating the various stem cell regulation pathways that lead proteins to develop into certain anatomical structures.
“In this study, we discovered how different signaling pathways work together to control stem cells,” says Chai, who is also director of the Center for Craniofacial Molecular Biology. “We can use this information as a playbook for tooth regeneration.”
The discovery means that, in time, a dentist might one day reach for a living tooth regenerated in a lab to replace a broken tooth instead of amalgam or porcelain, Chai explains.
The coauthors include researchers from USC’s Center of Craniofacial Molecular Biology; the Molecular Laboratory for Gene Therapy and Tooth Regeneration in Beijing; and the department of prosthodontics at Peking University School and Hospital of Stomatology.