Management of Young Permanent Teeth (Apexogenesis, Apexification and Regenerative Endodontics)

Traumatic injuries suffered by the anterior teeth mostly occur before completion of the root formation which may have consequences like inflammation or necrosis of the pulp. The most sensitive part of a young permanent tooth to trauma is the Hertwig’s epithelial root sheath (HERS). However, root formation can still continue to occur if there is a disruption of vascularity and cellularity in the apical region, even in the presence of pulpal inflammation and necrosis of the traumatized teeth. Hence, every effort should be made to maintain the viability of HERS as it acts as a source of undifferentiated cells which could give rise to the formation of the hard tissue and it also protects the tooth against the ingrowth of the cells of periodontal ligament into the root canal, which might result in intracanal bone formation and cessation of root development. In cases where complete destruction of Hertwig's epithelial root sheath occurs, the development of a normal root comes to a halt but, this does not mean that there is an end to the deposition of hard tissue in the region of the root apex. Although, once the sheath has been destroyed, there can be no further differentiation of odontoblasts but, the hard tissue can still be formed by cementoblasts which are present in the apical region or by fibroblasts of the dental follicle and periodontal ligament cells that undergo differentiation after the injury. This chapter is specifically oriented towards discussion of the viable methodology and treatment modalities of vital, nonvital immature young permanent teeth.