Introduction
infected instrumentation debris, periodontitis, necrotic
APICAL PERIODONTITIS, PERIODONTITIS, NECROTIC
The ultimate goal of root canal therapy is to prevent apical periodontitis or to allow healing of an existing-apical periodontitis by rendering the root canal system as free as possible from microorganisms. This is accomplished by disinfecting the whole root canal system through meticulous shaping and irrigation [Most often clinicians deal with narrow curved roots in which there is more than one canal, those canals are usually connected through fins or anastomoses. An anastomosis -also called an isthmus- is a narrow space between two root canals that can harbor microorganisms and dentin debris packed into it during instrumentation [Sodium hypochlorite (NaOCl) is the most used irrigating solution. It has a strong antimicrobial effect with the ability to dissolve organic tissue [Anastomosis is a restricted area that harbors remnants of pulp tissue, bacterial biofilm and infected instrumentation debris especially in infected necrotic root canals thus it must be cleaned and disinfected to achieve a favorable outcome, it is well-agreed that the anastomosis cannot be touched by the instruments and is a very difficult area to be reached by the irrigant [The null hypothesis of this study is that there is no significant difference in anastomosis cleanliness at different anastomosis levels between passive ultrasonic irrigation (PUI) using Irrisafe (Satelec, Acteon, France), sonic activation using EDDY, and the control group needle irrigation without activation (NA).