The discovery not only suggests a biological method to repair dental problems, but also points to the existence of dental stem cells which could be manipulated to grow into many forms of dental tissue, said John D. Bartlett, an assistant professor at the Harvard Medical School who worked on the research team.
“Long term, this work may lead to methods for reconstituting the components of teeth to replace restorative materials like amalgam,” R. Bruce Donoff, dean of the Harvard School of Dental Medicine, wrote in an e-mail. “If a functioning biologic tooth were to be developed for human use, it would challenge dental implants as an alternative.”
While other teams have successfully grown partial tooth structures in labs, this is the first time researchers have also produced enamel, the hard outer layer of a tooth.
“To have both dentin and enamel juxtaposed with each other is what was most exciting,” Bartlett said.
The work was initiated by a seed grant from the Medical School, which founded the Center for Craniofacial Tissue Engineering in 1999 with the aim of creating a biologic tooth, Donoff said.
The team created the teeth by taking unerupted pig tooth buds, breaking these tissues down to the cell level and coating a scaffold—or tooth mold—with as many cells as possible. The scaffold was then implanted in the blood-rich intestinal lining of rats.
After about 30 weeks, researchers were able to remove several recognizable tooth crowns, each a few millimeters wide, composed of dentin, odontoblasts (cells that secrete proteins which form dentin), a pulp chamber (the innermost part of the tooth, containing nerves) and enamel.
“The elegance of this work is how well it worked. I think all involved were a bit surprised,” Donoff said.
More than a decade of research is needed before the method could be suitable for use with humans, Bartlett said.
The tooth grown in the lab did not conform to the shape given by its scaffolding, and researchers will also have to determine how to encourage root growth.
Ultimately, doctors may be able to take human dental cells and induce them to grow into usable teeth, Bartlett said.
“The most important issues relate to improving our knowledge of the interactions needed for tooth development,” Donoff said.
The researchers’ findings will be published in the Oct. 1 Journal of Dental Research.