This book deals with the rationale and techniques for treatment of the non-vital immature tooth. The importance of careful case assessment and accurate pulpal diagnosis in the treatment of immature teeth with pulpal injury cannot be overemphasized. The treatment of choice for necrotic teeth is apexification, which is induction of apical closure to produce more favorable conditions for conventional root canal filling. Apexification has been a routine practice for such teeth for many decades, and despite recent methods with mineral trioxide aggregate, ultimately there has been no major breakthrough to improve this treatment. The introduction of two new concepts namely, revitalisation and pulpal revascularisation have revolutionised the concept of apical closure in immature permanent teeth.