There is a paradigm shift in the treatment of pulpally involved primary teeth over the past few years. The initial concept of extraction has long been replaced by preservation of teeth by various endodontic therapies. A good bio-mechanical preparation forms the hallmark of a successful endodontic therapy. A new horizon has opened up with the introduction of NiTi instruments in dentistry. These instruments due to their shape memory property and super elasticity have revolutionized endodontic treatment. This book gives an insight into the the evolution of rotary systems over time, various systems available in the market and strategies for their use. This book also gives a review on modification of techniques for instrumentation in deciduous teeth.