Researchers use stem cells to create living dental implants (1/23/2007)

Right: Pig Lower Incisor, Left: Hybrid Living-fabricated Dental Implant

USC School of Dentistry researcher Songtao Shi, DDS, PhD, has regenerated tooth root and supporting periodontal ligaments to restore tooth function in 4-8 month-old pigs.

Dr. Shi's research goal is to create a dental implant that can be used in a patient who's jaw bone isn't structurally strong enough for supporting dental implants.

Dr. Shi, and his multi-national team, started by acquiring 18 wisdom teeth extracted from sixteen adults at the Dental Clinic of the National Institute of Dental & Craniofacial Research (NIDCR). His team then separated the root apical papilla from the surface of the root. Several stem and progenitor cells were discovered, and each where cultured to create quantities suitable for testing.

The stem cells were then tested to determine what type of tissues they could transform into. This process, called differentiation, led to the discovery that they could turn into cell types such as fat cells, ligaments, dentin and bone. The stem cells were tested both in the lab and in mice.

By determining which stem cells were capable of creating the root structures in humans, they then harvested the same cells in pigs. Pigs where used because of the close similarities between pig and human dental tissues.

After harvesting and culturing the pig's apical papilla stem cells, they then seeded a bio-degradable scaffold, in the shape of the tooth root to be replaced. The root was then implanted in the same fashion that a dental implant is inserted.

The root was then sealed under the gums and given 3 months to grow. While the root structure formed and took hold in the jaw, the bio-degradable scaffold was absorbed by the body, leaving only natural tooth root.

At the end of the 3 months the root was unsealed and a pre-fabricated porcelain crown resembling a pig incisor was inserted and cemented on top of it.

After 4 more weeks the newly implanted incisor was compression tested to determine if it was as strong as a real tooth. The tested showed that they were stronger that normal dental implants, but not quite as strong as a real tooth. Refinement of the process may yield better results as the technology progresses.

He hopes to conduct clinical trials within the next several years, great news for dental patients who are not candidates for dental implants or would prefer living tissue derived from their own teeth.

Because the regeneration of a tooth requires harvesting stem cells from living teeth, Dr. Shi believes that wisdom teeth may be "banked" for use in later life. He notes that their survival in freeze-thawing requires additional research.

Several companies, including BioEden Baby Teeth Cell Bank, in Austin, Texas claim that they can collection, process, and cryopreserve stem cells obtained from the baby teeth of young children.

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