The biomechanical preparation of curved root canals is an important consideration in endodontic treatment. In addition to the canal instruments and preparation techniques,root canal morphology and the degree of curvature are determining factors in endodontic root canal preparation. Difficulties in the preparation of curved root canals have prompted the development of new preparation methods and investigations of root canal geometry. Dental pulp sometimes shows the phenomenon of dystrophic calcification or calcific metamorphosis. Calcific metamorphosis is defined as a pulpal response to trauma that is characterized by deposition of hard tissue within the root canal space. This may occur following direct pulp capping/mineralization in response to various irritants, aging or trauma or sometimes idiopathically. This mineralization can be so extensive that the entire root canal system is obliterated. As a result root canal treatment in such cases may become difficult if not an impossible task. The objective of this book is to review and discuss the combination of various instruments and techniques used in the management of curved canals and calcified canals.