Tissue regeneration requires an interaction of stem cells and growth factors in a bioactive scaffold. This study utilized the ferret canine as an in situ animal model to investigate a clinically applicable tissue engineering approach for dentin-pulp regeneration. On the other hand, ideal root canal disinfection for dental pulp regeneration is a challenge. There is no study available to address the effect of residual bacteria on the outcome of dental pulp regeneration in previously infected root canals. Therefore, the aim of this study was two-fold: 1) To determine histologically, the efficacy of delivering stem cells within a bioactive scaffold directly into the root canal space compared with the traditional revascularization method and 2) to determine the effect of residual bacteria on the histological and radiographic outcomes of dental pulp regeneration procedures.