64 страниц. 2012 год. LAP Lambert Academic Publishing The most important objective of root canal therapy is to minimize the number of microorganisms and pathologic debris in the root canal system. Thorough instrumentation of the canal has long been considered to be an essential component in the cleaning and shaping process. Mechanical instrumentation and irrigation are sound endodontic principles and essential components of successful endodontics. Clinicians desire easier and faster endodontic therapy. Manufacturers developed nickel-titanium rotary instrumentation systems to facilitate the cleaning and shaping process. They are popular because of their apparent ease of use and reduced number of instruments. Protaper rotary instruments have recently enjoyed a wide popularity. This study is intended to know the effect of increased canal enlargement by protaper rotary instruments in reducing the number of intracanal bacteria.