The goal of this clinical trial is to learn which of three common root-canal rinsing (irrigation) methods removes bacteria most effectively in adult patients who need root-canal treatment. The main questions it will answer are: How much does a chitosan solution used alone lower the number of bacteria inside the root canal? Do the combinations sodium hypochlorite + chitosan or sodium hypochlorite + EDTA lower bacteria even more than chitosan alone? Researchers will compare the three irrigation methods to see which one achieves the greatest bacterial reduction. What participants will do Be randomly assigned to one of three groups: Group 1: Chitosan only Group 2: Sodium hypochlorite followed by chitosan Group 3: Sodium hypochlorite followed by EDTA Attend two clinic visits: Visit 1: Receive standard root-canal treatment under local anesthesia. Provide tiny paper-point samples from inside the canal before and after the assigned rinse (painless; takes seconds). Visit 2 (about 1 week later): Return for a check-up and final filling of the tooth. Record any pain or discomfort for the first three days after treatment in a simple diary (or by phone). About 90 adults will take part. All procedures are routine in dental care, and there is no cost to participate. Participants may withdraw at any time and can ask the study dentist any questions throughout the trial.