# Signal discovered that triggers tooth regeneration in humans

Scientists from the Stomatological Hospital of Sichuan University have made an important discovery: they identified a molecular signal capable of triggering tooth tissue regeneration. The key role in this process is played by the protein SMAD7, which activates the Wnt/beta-catenin signaling pathway — one of the main mechanisms of regeneration. The results of the study were published in the International Journal of Oral Science (IJOS).

Damage to the dental pulp — the soft tissue inside the tooth where nerves and blood vessels are located — often results from trauma or advanced tooth decay. In such cases, inflammation begins, the tissue gradually dies, and the tooth loses its vitality. Even the most advanced regenerative endodontic techniques are far from always capable of reliably restoring living tissue.

The research team turned to the signaling pathways of pulp stem cells — the very mechanisms that control their division and transformation into new dental tissue cells. Of particular interest was the protein SMAD7. Until now, it had been considered primarily an inhibitor — a "brake" on signaling processes within the cell.

However, experiments with human dental pulp stem cells yielded a surprise. It was found that SMAD7 directly interacts with beta-catenin in the cell nucleus and enhances the activity of the Wnt/beta-catenin signaling pathway. It is precisely this pathway that activates genes responsible for stem cell division and their differentiation into cells involved in tissue repair.

Simultaneously, SMAD7 suppresses signals from another cellular pathway — TGF-beta, which can limit beta-catenin activity. Thanks to this dual action, beta-catenin remains available in the cell nucleus and continues to stimulate regeneration processes.

The authors of the study emphasize that the discovery demonstrates that SMAD7 performs not only the function of a signaling pathway "brake" but also acts as an active regulator of tissue regeneration. Understanding this mechanism paves the way for developing fundamentally new approaches to treating pulp injuries.

In the future, targeted intervention in the interaction between SMAD7 and beta-catenin could enhance the tooth's natural regenerative capacity. Moreover, the findings may find application in other areas of regenerative medicine, since the Wnt signaling pathway plays a crucial role in bone tissue repair and craniofacial structure development.