What Teeth May Come.

From the WebMD Archives

Reviewed by Dr. Aman Shah

Nov. 1, 2000 -- Your teeth are the hardest part of your body, but they aren't indestructible -- just ask some of the rough and tumble sports heroes whose choppers didn't withstand the last fist, elbow, or hockey puck that found its way to their mouths.

Dentists have long repaired teeth by mending them with silver, gold, or ceramics, or by making dentures. But now researchers believe that they may have begun to unravel the genetic factors responsible for tooth formation. This may allow them to grow new teeth for you using your own cells.

"We've cultivated mice teeth in a laboratory dish," says Mary MacDougall, PhD, associate dean of the University of Texas Health Science Center Dental School in San Antonio. She tells WebMD that the cells that make teeth usually die after your teeth formed, but the scientists have found a way to regenerate them.

"We've dissected out human cells that make enamel and dentin," MacDougall says. She explains that by adding a "cancer" gene, they have been able to make these cells grow and divide indefinitely instead of dying out.

This means constant division in a petri dish of cells that make enamel, the white outer tooth layer, and dentin, a hard, mineral layer under it. MacDougall's team and its collaborators at the University of Missouri at Kansas City are using this technique to make natural enamel and dentin.

"We're looking at this as a replacement for amalgam [silver used for filling cavities]," MacDougall tells WebMD. This natural, biological material would afford better bonding and better matching than current artificial fillings.

MacDougall's successful investigation thus far into gene regulation of tooth formation in mice led to a recent $4.6 million National Institute of Dental and Craniofacial Research grant. The scientists believe the funding will allow them to expand their research so that in about 20 years, they will be able to regenerate your own teeth in your mouth.

This would mean much to the aging American population.

"Tooth loss is a big problem because people are living longer," says Ali Bolouri, DDS, a professor of restorative sciences at Baylor College of Dentistry in Dallas. But he tells WebMD that age is not the only factor in losing your choppers. Loss of calcium in the body, smoking, diet, and dental hygiene also play roles.

Bolouri says researchers already are regenerating bone to which teeth are anchored. Bone deterioration, or severe periodontal disease, is a problem for replacing teeth because the bone won't hold dentures or implants.

Because of this, MacDougall says there is a new incentive to learn more about tooth regeneration.

"We are now looking at making human teeth in a laboratory dish that could be used instead of implants on titanium posts," she says. "They would look better, wear better, and last longer then current implants."

Implants sometimes don't work because the artificial materials don't bond with the bone, and there can be severe problems with inflammation or the body may even reject the foreign material, MacDougall says. Using cells from a person's body to grow a new tooth should overcome these problems.

Although all the cells in your body have the same genes, different genes are active in different cells that allows, say, a liver cell to function differently from a skin cell. MacDougall and her colleagues are tracking down the subset of genes that function only when teeth are forming. Once the researchers have this information, she believes that they can use the genes to correct orthodontic diseases.

"We think we can do this by injecting these specific genes into the developing teeth," MacDougall explains. "We can treat every individual tooth as an individual organ. This genetic information would not make sense to cells in other parts of the body since these are specific to teeth."

The information also would allow scientists to develop genetic screening tests to determine who is at greatest risk for tooth decay and periodontal disease. Then doctors could use the gene therapy to prevent or treat these disorders, MacDougall theorizes.

MacDougall -- who began this line of research 15 years ago -- believes that tooth regeneration and gene therapy will be available for people of all ages. She says it will be especially important for children who receive trauma to the mouth, and aging baby boomers and their children.

"The U.S. population is graying and they want to keep their teeth longer; they don't want to wear dentures," MacDougall says.

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