From biofilm disinfection to bacterial stem cell modulation and dentin matrix-driven stem cell mineralization

Caries or trauma are common occurrences in the permanent dentition of young patients. They often result in pulp necrosis, root canal infection, inflammation (apical periodontitis) and arrest of further root development. The consequences for the young patients can be overwhelming, ranging from intense pain to tooth loss. Currently, biological-based approaches exploiting patients’ own stem cells (revitalization treatment) are becoming more popular. They predictably achieve resolution of pain and inflammation and often succeed to promote further root development. Despite the favorable outcomes, the predictability of revitalization treatment has been questioned. Bacterial biofilms, the nature of stem cells and the quality and quantity of the bioactive stem cell guiding molecules released from the root canal are factors that may influence the treatment outcome.In the first part of this thesis, we investigated the anti-biofilm capacity of several root canal irrigants used during revitalization treatment. For the first time, we demonstrated that biofilm structure itself affects the action of the irrigants against biofilms. Next, we provided evidence that the balance between the unfavorable inflammatory and the favorable mineralizing stem cell phenotype can be regulated by specific cell surface receptors (TLR2) activated by bacterial and biofilm components. In the final part, we explored the mineralization capacity of several stem cell populations eligible for revitalization treatment, under the guidance of bioactive molecules derived from tooth dentin. We believe that the findings presented in this thesis could contribute in the optimization of revitalization clinical treatment protocols. That could increase treatment success and predictability