The book consists of seven chapters. Chapters 1 and 2 deal with the goals of canal shaping through the evolution of the principles of biomechanical reaming. Chapter 3 recounts the important evolution of nickel-titanium instruments. Chapters 4-5-6 cover the various stages of canal preparation, while Chapter 7 deals with the topic of cleaning the canal system. The latter topic is particularly important since mechanical cleaning alone is currently unable to decontaminate the endodontic system, a much more complex system when analysed three-dimensionally, unreachable by contact with instruments even in some areas of the main canal, more likely to be reached through a chemical decontamination action by specific irrigation solutions. Therefore, based on the current state of the art and current technological progress, the interaction between mechanical procedure and chemical/physical procedure provides the best results in terms of decontamination of the root canal system.