Solutions: Saving Decayed Teeth with Stem Cells

Can decayed young teeth be saved with stem cells? Dr. Renato Silva thinks so.

When decay penetrates the nerve space in an adult’s permanent tooth—known as dental pulp—a root canal is the best solution. A dentist removes the nerve and pulp, and then cleans and seals the inside of the tooth.

But when that same problem occurs in a child or young adult, a root canal becomes much trickier, because the root of the tooth may not be fully formed. Dentists might try to clean and fill the root canal, or they might pull the tooth and replace it with an implant when the patient is older.

“We see a lot of kids come into our endodontic clinic and pediatric clinics with dental problems,” said Silva, D.D.S., Ph.D., associate professor and chair of the department of endodontics at The University of Texas Health Science Center at Houston (UTHealth). Factors that contribute to decay include not brushing and/or flossing, diet, saliva composition and genetics.

Depending on the age of the child, a permanent tooth will come in, but the root may take a few years to develop, said Ariadne Letre, D.D.S., Ph.D., director of research in the department of endodontics at UTHealth’s School of Dentistry and a member of Silva’s team.

Rather than choosing a root canal treatment or tooth extraction for young permanent teeth, Silva believes he can use stem cells to replace the damaged tissue with healthy tissue and promote root formation.

His research is in the preclinical stage, but results so far have been promising.

A microscopic image of tissue invagination into the tooth after 45 days of implantation.

Dental pulp is a complex bundle of tissue, blood vessels and nerves. The tissue dies when it is contaminated by bacteria. During a root canal, a dentist will dig out that contaminated tissue and replace it with an artificial material, Silva said, because you can’t leave an open space for bacteria to continue to grow. Even so, root canal therapy treated teeth are destined to be brittle and devitalized.

But what if there was a way to revitalize the tissue and make the tooth healthy again?

While pondering ways to promote root formation, Silva and his team came up with the idea of using stem cells retrieved from the root area deep inside the tooth called the apical papilla. Since they also needed some sort of scaffold for the cells, they devised one made of a polymer fiber impregnated with a protein called vascular endothelial growth factor (VEGF), to stimulate the growth of new blood vessels that would help with tissue and pulp regeneration.

“These stem cells of the apical papilla can turn into any type of tissue, and in our case, we need root and pulp tissue, so we thought, ‘Why not?’” Silva said.

After removing the decay from the tooth and cleaning out the root canal, Silva and his team fill in the area with stem cells and the VEGF scaffold, which will regenerate the pulp tissue, he said.

The stem cells come from extracting the third molar of the child—known as the “wisdom” tooth. Silva and his team collect the cells attached to the bottom of the tooth crown, isolate the stem cells and then use them in the decayed tooth.

Because the use of stem cells for dental treatment in humans is not yet approved in the United States, Silva and his team have been researching their theory on mice. After putting the stem cells inside the tooth, they implant the teeth on the back of mice to evaluate new tissue formation. The result has shown that the tissue and blood vessels from the mouse go inside the root and fill in the empty space, mimicking the original dental pulp tissue.

Once the use of stem cells is approved for this use, Silva and his team will move forward with isolating the stem cells of the apical papilla from third molars to deliver into the decayed tooth of the same patient.

“I believe our results are promising in light of future patient-centered approaches toward pulp and dentin regeneration therapies,” Silva said.