Using Stem Cells from Teeth to Regrow Injured Teeth

An interesting article titled “Deciduous autologous tooth stem cells regenerate dental pulp after implantation into injured teeth,” by Xuan et al. appears in Science Translational Medicine (vol. 10, no. 455, 2018, Published August 22, 2018). The article discusses the results of a clinical trial using stem cells extracted from baby teeth to regrow tissue in teeth that have been injured. In the past articles on this site have discussed storing wisdom teeth stem cells with the hopes that they could one day be used to heal other body tissues. While this study did not use stem cells from wisdom teeth, but instead stem cells from baby teeth, it helps demonstrate some of the possibilities that may exist in the future.

In the study by Xuan et al., the authors were motivated by some previous studies with mice. A further motivation was that many young children experience trauma in their permanent teeth which can lead to loss of vital dental pulp, loss of the blood and nerve supply, and impaired root development, leaving what is often referred to as a “dead tooth.” This often happens from kids playing around or tripping and falling. The standard of care for such injuries is apexification that encourages tooth root development and closure of the root apex through hard tissue deposition but is unable to restore lost pulp tissue and root development thereafter occurs abnormally. In the study, 40 patients between ages 7 and 12 were randomized into two groups, where each patient had an injured tooth and still had baby teeth. The first group contained 30 patients that received implantation of autologous human deciduous pulp stem cells extracted from their baby teeth and the second group contained 10 patients that received standard apexification. Four patients from the stem cell treatment group were excluded due to loss of follow up and trauma, which resulted in 36 patients eligible for a 12 month follow-up.

Cone-beam computed tomography (CBCT) images of roots were taken before stem cell implantation or apexification and also at 6 and 12 months after treatment. In patients who received stem cells the length of the root was increased and the apical foramen was closed at the 12 month mark which did not occur for those who received apexification. In patients who received stem cells there was increased dentin thickness (the hard part of the tooth below the enamel) observed at both the 6 and 12 month mark but this did not occur in those who received apexification. The researchers also found that those who received stem cells had a mean increase in vascular formation (blood flow). The researchers found that only those who had treatment with stem cells had regained some sensation of the tooth that was injured. In one patient who received stem cell treatment on the injured tooth, it was reinjured and had to be extracted. Based on histology and immunofluorescence staining they found the implanted stem cells regenerated different components of dental pulp along with nerve regeneration.

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The authors did not observe any significant side effects in the 36 patients who received stem cells that were observed at 12 months. They also evaluated 20 of these patients for another 12 months who had received stem cells (another six patients from this group were lost from the original 30). They found that blood cell numbers were within normal ranges. They believe the stem cell implantation into the injured teeth had no effects on the patient’s immune response, liver function, renal function, and myocardial function 24 months after treatment. They further tested the 20 teeth in these 20 patients and believed the dental pulp remained viable at the 24 month mark. The authors are also extending their observation period of these patients for even longer. Statements made by one of the study authors suggests that follow up data from 2.5 to 3 years also demonstrates safety and effectiveness (see the article titled “Regrowing dental tissue with stem cells from baby teeth” written by Katherine Unger Baillie on September 11, 2018, at Penn Today).

While the authors demonstrated that using a person’s own stem cells from baby teeth can be used to regenerated injured teeth, they are not sure if these results translate to using someone else’s stem cells. For example, this could be useful in cases where a person has lost all their baby teeth and thus the stem cells can not be harvested. Thus the researchers are testing the use of allogenic stem cells which are donated from another person in order to explore regenerating dental tissue in adults.

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