 The aim of this prospective in vivo randomized clinical trial to evaluate influence of combination of calcium Hydroxide CALCIPAST Paste, Poland and chlorhexidine Gel 2 Gluco-Chex 2, Cerkamed, Poland in comparison to calcium hydroxide paste CALCIPAST Paste, Poland as Intracanal Medication on post operative pain incidence, degree, duration and reduction of bacterial endotoxins quantitative after endodontic treatment in single rooted necrotic teeth. 