**1. Introduction**

Stem cells have been opening a promising future in clinical therapies because of their two remarkable features known as self-renewal and multi-lineage differentiation. These cells can be classified in terms of their origin (embryonic, prenatal and postnatal stem cells) as well as the differentiation commitments (pleuripotent, multipotent and unipotent). Postnatal stem cells, also known as the adult stem cells (ASCs), normally exist in almost every adult tissues, including bone marrow, skin, neural tissues, and dental epithelium, acting as supportive cells by their regeneration capacity. Among different stem cell types, ASCs seem to be more applicable in stem cell-mediated therapies and regenerative medicine because these cells lack ethical concerns, and possesses less tumorgenic potency than their embryonic counterparts.

Recently, human dental stem cells (DSCs), a subtype of ASCs, have drawn worldwide attention for future therapies due to their both technical and practical superiorities. In addition to having some mesenchymal stem cell (MSC) characteristics, including plastic adherent ability with formation of colonies in vitro, and also immunoprivileged properties, DSCs are easilyaccessible cells with higher proliferation capacity than ordinary marrow-derived MSCs. Currently, there are six types of stem/progenitor cells determined in dental-related tissues. 1) dental pulp stem cell (DPSCs), 2) stem cells from human exfoliated deciduous teeth (SHED), 3) periodontal ligament stem cells (PDLSC), 4) stem cells from apical papilla (SCAP) of developing tooth, 5) dental follicle stem/progenitor cells (DFPCs) and 6) gingiva stem cells (GSCs). DPSCs, SHEDs and SCAPs are referred to as dental pulp-related stem cells, and PDLSCs & DFPCs as periodontium-related stem cells [1, 5].

properly cited.

© 2013 Karamzadeh and Eslaminejad; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This chapter focuses on different aspects of dental-derived adult stem cells, such as their classification, biological characterization, initiating culture, cultivation systems, cryopreser‐ vation and potential applications in tissue engineering and regenerative medicine. The data are organized as three main parts, including: 1) Dental-related stem cell biology: from the classification to the characterization and differentiation potential 2) Dental-related stem cell initiation culture, culture systems and cryopreservation 3) Dental-related stem cell- based tissue regeneration.
