The ultimate goal of root canal therapy is either prevention or treatment of apical periodontitis. Procedure includes effective cleaning and shaping to remove all pulp tissue, bacteria and their by-products, provide adequate canal shape and to obtain a three-dimensional obturation. But during instrumentation, necrotic debris, residual pulp tissue, microorganisms, dentin chips or irrigants can be forced towards the periapical area. This may lead to an inflammatory “flare-up” reaction characterized by pain, swelling or both & are severe enough for the patient to seek emergency treatment. The causes of flare-ups are numerous and these are often multifactorial. This book will address “Apical Extrusion of Debris” which is a considered as a factor of prime importance for this reaction. All instruments and different preparation techniques have been reported to cause varying degree of apical extrusion of the infected debris, even when the preparation is kept short of the apical foramen. We are comparing hand instrumentation techniques with the different rotary NiTi File systems.