Necrotic Teeth With Chronic Apical Periodontitis

The goal of this clinical trial is to learn if nanochitosan can achieve regeneration in mature necrotic teeth. It will also provide data about the healing potential \& postoperative pain after using different irrigation protocols. The main question it aims to answer are: Does nanochitosan can demonstrate clinically successful outcome, minimize postoperative pain \& flare ups? What is the regenerative potential of mature necrotic teeth with chronic apical periodontitis? Is regeneration an alternative treatment modality for mature necrotic teeth with apical periodontitis? Researcher will compare the regenerative potential \& postoperative pain after using 2.5% NaOCl+ 17% EDTA, 1% nanochitosan \& 1% nanochitosan+17% EDTA to see if 1% nanochitosan alone or when used with 17% EDTA can enhance regeneration. Participants' root canals will be: Divided into 3 groups \&irrigated thoroughly by the different irrigation protocols (2.5% NaOCl+ 17% EDTA, 1% nanochitosan \& 1% nanochitosan+ 17% EDTA) Regenerative procedures will be done Clinical sensibility test \& radiographic changes will be evaluated at 6\&12 months follow up periods Detection of inflammatory mediators from GCF at 6 months follow up periods to be compared with its preoperative levels as a predictor for success or failure Assessment of postoperative pain using Numerical Rating Scale at 6, 12, 24 hours then daily for 7 days