Introduction:In the new millennium, where biology and biotechnology have replaced chemistry, we are exploring “biological solutions to biological problems.” Owing to the extraordinary advances taking place in the field of cellular and molecular biology. Materials and Methods: This review article has two folds. First, a review on definition of different types of stem cells and their comparison, their characteristics, properties and the effect of environmental changes on them such as dental material, inflammation, aging and hypoxia. Second, a review on utilization of these stem cells in dental tissue engineering such as dentin pulp regeneration (odontoblast differentiation, dental pulp proliferation and regenerative endodontics). Results: There are two approaches to practice regenerative endodontics. One is to take the more conservative treatment approach for well-selected cases. The other is to promote tissue engineering technologies for dentin, pulp, cementum and periodontal ligament regeneration, which is already at the laboratory stage or in the field of animal studies. Conclusion: Post-natal human dental pulp stem cells (DPSCs) represent a unique precursor population in the dental pulp, which is multipotential and can regenerate a dentin/pulp-like structure. They are specific mesenchymal stem cells that exist in human dental pulp tissues and can be induced to differentiate into odontoblasts, adipocytes and neural-like cells in vitro. in vivo transplantation has demonstrated that DPSCs were capable of forming dentin-pulp-like tissue. SHED cells are distinct from DPSCs by virtue of their higher proliferation rate, increased cell population doublings and osteoinductive capacity in vivo. Although SHEDs are able to differentiate into putative odontoblasts and are immunoreactive to dentine sialophosphoprotein, they failed to reconstitute a complete dentin–pulp complex which was observed with DPSCs. The dental papilla at the apex contains stem cells (SCAP) that have been recently described to be more robust stem cells than DPSCs. The SCAP may survive the infection to allow root maturation while the survived DPSCs in the remaining vital pulp rebuild the lost pulp tissue in the canal and may give rise to substitute the damaged primary odontoblasts.