Activation of α SMA expressing perivascular cells during reactionary dentinogenesis

Aim To examine the contribution of perivascular cells expressing α SMA to reactionary dentinogenesis. Methodology An inducible, Cre‐loxP in vivo fate‐mapping approach was used to examine the contribution of the descendants of cells expressing the α SMA ‐Cre ERT 2 transgene to reactionary dentinogenesis in mice molars. Reactionary dentinogenesis was induced by experimental mild injury to dentine without pulp exposure. The Student's t test was used to determine statistical significance at * P  ≤   0.05. Results The lineage tracing experiments revealed that mild injury to dentine first led to activation of α SMA ‐tdTomato + cells in the entire pulp chamber. The percentage of areas occupied by α SMA ‐tdTomato + in injured (7.5 ± 0.7%) teeth were significantly higher than in teeth without injury (2 ± 0.5%). After their activation, α SMA ‐tdTomato + cells migrated towards the site of injury, gave rise to pulp cells and a few odontoblasts that became integrated into the existing odontoblast layer expressing Col2.3‐ GFP and Dspp . Conclusion Mild insult to dentine activated perivascular α SMA ‐tdTomato + cells giving rise to pulp cells as well as a few odontoblasts that were integrated into the pre‐existing odontoblast layer.