International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 Volume 6 Issue 5, May 2017 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Influence of Irrigants and Intracanal Medicaments on the Vitality of Stem Cells from Apical Papilla - An Overview Krasimir Hristov 1 , Nataliya Gateva 2 , Pavel Stanimirov 3 1 Medical University of Sofia, Faculty of dental medicine, Department of Pediatric dentistry 2 Medical University of Sofia, Faculty of dental medicine, Department of Oral and maxillofacial surgery Abstract: Regenerative endodontics includes a therapy with new populations of mesenchymal stem cells, which are present in the apical papilla of teeth with incomplete root development, called stem cells from apical papilla. The preservation of these cells in the treatment of immature teeth may allow the continuation of root development to its final form and the closure of its apex. The choice of irrigants and intracanal medications in regenerative endodontics must be made taking into consideration their impact on the vitality of SCAP, in addition to their bactericidal/static effect. Keywords: immature teeth, regenerative endodontics, stem cells from apical papilla 1. Introduction The endodontic treatment of immature permanent teeth with necrotic pulp is both a clinical problem - a challenge for the clinician, as well as a public health problem. Regardless of ability to apply the apexfixation procedure, the long-term prognosis for these teeth is questionable due to the small and incompletely formed root walls [1]. Regenerative endodontics has become a real alternative for the treatment of such teeth. It also includes a regenerative therapy with new populations of mesenchymal stem cells, which are present in the apical papilla of teeth with incomplete root development [1,2]. They are called Stem cells from apical papilla (SCAP). Although they exhibit similar characteristics to those of the dental pulp stem cells (DPSCs) discovered much earlier, they have a different appearance, which is assessed by methods of histology, immunohistochemistry, cell and molecular analysis [2]. Evidence is accumulating to support the hypothesis that SCAP are likely sources of primary odontoblasts, which are responsible for the formation of root dentin, while DPSCs are a possible source of replacement/spare odontoblasts [2]. The preservation of these stem cells in the treatment of immature teeth may allow the continuation of root development to its final form and the closureofits apex [2]. In ‘Late bell’ stage, when the formation of the dental crown has started, the dental papilla (papilla dentis) gradually changes its position by moving apically to the dental pulp. The first odontoblasts appear, the dentinogenesis is initiated and the formation of the root begins, alongside the formation of a double-layered epithelial vagina called ‘Hertwig's epithelial root sheath’ [3]. It is assumed that these epithelial cells play an extremely important role in the formation of the tooth root, although the exact nature of this process is not fully understood [4]. Among the various functions attributed to these cells are the inducer function and the regulator functionof root formation - dentinogenesis, cementogenesis and the formation of the periodontium, the determination of size, shape and number of roots [3,5,6]. It is also believed that they secrete chemotactic proteins in the basal membrane that guide the migration of precementoblasts [4,7] or they themselves may undergo epithelial-mesenchymal transformation and become cementoblasts [8]. The histological characteristics of the connection between the pulp and the apical papilla have not yet been well- described, but it has been shown that the latter has a unique supply of mesenchymal stem cells [7]. Due to its apical localization, this tissue is also important because of its collateral circulation, which allows it to survive the pulp necrosis [2]. The apical papilla and its intrinsic stem cells (SCAP) were first described in 2006. This papilla is a rich reservoir of undifferentiated mesenchymal stem cells with great potential for proliferation and odontogenic differentiation [2,9,10]. The proximity of the apical papilla to the apex of the tooth and its natural seamless connectivity with the root canal area makes this rich source of stem cells easily accessible for regenerative endodontic procedures [9]. The overall root development of permanent teeth ends about three years after their eruption. For most teeth this process occurs during childhood and adolescence. It is a time during which the developing tooth can be affected by various factors that can lead to pulp degeneration and infection of the root zone. Such factors include carious lesions, traumatic injuries, development abnormalities of the teeth [11]. Unlike teeth with complete root development, pulp necrosis in immature teeth does not exclude the presence of residual pulp progenitor cells in the apical third of the root. In those teeth, because of their anatomical and physiological characteristics, accomplishing the objectives of conventional root canal treatment is difficult [12]. Mechanical cleaning is almost impossible, and the removal of necrotic debris from this wide canal is hindered. Even if that happens, the root remains short, with thin walls and prone to fracture. Some of the technological difficulties can be overcome by conducting apexfixation with calcium hydroxide or an apical barrier Paper ID: ART20173195 DOI: 10.21275/ART20173195 999