Immature necrotic permanent tooth presents a distinctive challenge for the endodontist. Various treatment modalities have been employed to create hard tissue barrier at the apex, which includes non-vital pulp therapy with calcium hydroxide, apexification with mineral trioxide aggregate, biodentin. This book tries to give an insight of various treatment plans for management of immature apex depending upon the pulpal status of the tooth, also it describes novel treatment modalities like regenerative endodontics which involve the physiological replacement of the damaged tooth structures. It focuses on the terminologies, history, various newer bioactive materials and recent trends in the management of open apex. this book is easy to read, student-friendly chapters with collective information in a single book. A list of references is also provided to encourage further readings. Flow charts and diagrams are incorporated where needed. A deep understanding and abiding love for the subject has been given in the making of this book.