When an adult tooth is lost, it does not naturally grow back. Unlike primary “baby” teeth, which are naturally replaced, permanent teeth are a one-time set. This difference in regenerative capacity makes regrowing adult teeth a compelling area of scientific inquiry.
Why Adult Teeth Don’t Regenerate Naturally
Adult human teeth possess a very limited natural regenerative capacity. This limitation stems from dental stem cells, active during initial tooth formation, becoming largely dormant once adult teeth are fully developed. While specialized cells like odontoblasts remain in the pulp, their regenerative ability is significantly restricted after a tooth has fully formed.
Humans are classified as “diphyodonts,” meaning they develop only two sets of teeth: primary deciduous and permanent. After permanent teeth erupt, biological structures responsible for tooth development, such such as the dental lamina, largely regress. This means no additional “tooth buds” wait to replace a lost adult tooth.
The complex anatomy of a tooth further contributes to this lack of natural regeneration. A tooth is composed of multiple distinct tissues: outer enamel, dentin, inner pulp, and cementum that anchors it to the jawbone. Enamel, the hardest substance in the human body, is particularly challenging as it lacks the living cells necessary for regeneration once formed. This contrasts with bones, which possess a rich supply of active stem cells and blood flow, enabling them to heal and remodel over time.
Current Scientific Approaches to Tooth Regeneration
Despite natural limitations, scientific research actively explores methods to induce tooth regeneration. One promising avenue involves harnessing stem cells. Researchers investigate dental pulp stem cells (DPSCs), found within the soft tissue inside teeth, which show potential to regenerate both dentin and pulp. These cells are multipotent and exhibit a high proliferation rate, making them an accessible and reliable source for regenerative therapies.
Another focus is on induced pluripotent stem cells (iPSCs), adult cells reprogrammed to mimic embryonic stem cells. These iPSCs offer broad differentiation potential and present fewer ethical concerns than embryonic stem cells. Studies indicate iPSCs can differentiate into various dental epithelial and mesenchymal progenitors, contributing to the regeneration of dentin-pulp complexes, periodontal ligaments, and alveolar bone. Clinical trials are underway for pulp regeneration using a patient’s own (autologous) and donor (allogeneic) dental pulp stem cells.
Gene therapy also holds promise in activating dormant regenerative pathways. Researchers identified the USAG-1 gene, which normally inhibits tooth development. Suppressing this gene, often through specific antibodies, has stimulated the growth of new, whole teeth in animal models like mice and ferrets. This research progressed to human clinical trials, which began in Japan in September 2024, to translate these findings into clinical reality.
Biomaterial scaffolds represent a third approach, providing a structural framework to guide new tissue growth. These engineered scaffolds, made from natural materials like collagen or synthetic polymers, serve as a supportive environment for cell attachment and proliferation. Combined with stem cells, these scaffolds can facilitate the formation of bioengineered teeth or help regenerate damaged dental pulp, mimicking a tooth’s natural extracellular matrix.
What the Future Holds for Tooth Regrowth
Widespread clinical application of tooth regeneration faces several challenges. Replicating the intricate, multi-tissue structure of a natural tooth (enamel, dentin, pulp, and cementum) remains complex. Ensuring the regenerated tooth seamlessly integrates with the jawbone, gums, and nerve supply presents a significant hurdle. Achieving proper tooth morphology, ensuring long-term safety, and developing scalable, cost-effective procedures are also areas of ongoing research.
Despite these complexities, researchers are optimistic about the future of tooth regrowth. While widespread clinical applications are likely years or even decades away, some regenerative therapies could become available within the next 10 to 20 years. Specifically, gene therapy targeting the USAG-1 protein might be available as early as 2030, pending successful human trials.
If successful, tooth regeneration could transform oral healthcare by offering a biological alternative to artificial restorations like dentures and implants. This could lead to improved functionality and aesthetics for patients, and potentially “living fillings” that repair cavities by stimulating natural tooth tissue. Advancements in this field aim to usher in personalized dentistry, where new teeth or tooth components are grown using a patient’s own cells.