This study aims to assess the effect of Calcium Hypochlorite Versus Sodium Hypochlorite as Root Canal Irrigants on Postoperative Pain and Bacterial Reduction in Mandibular Premolars with Necrotic Pulps.

Inclusion Criteria:

1. Systematically healthy patient (ASA I, II).
2. Age between 20 and 55 years
3. Male or female.
4. Mandibular premolar teeth having single canals diagnosed with pulp necrosis with asymptomatic apical periodontitis.
5. Radiographic examination using Digora intraoral periapical sensor plate and software showing mandibular premolars with (0-2 mm) periapical radiolucency.

Exclusion Criteria:

1. Medically compromised patients having significant systemic disorders. (ASA III or IV).

2. History of intolerance to NSAIDS.

3. Teeth with:

   • Immature roots
   • Vital pulp tissues.
   • Association with swelling.
   • Acute peri-apical abscess or acute exacerbation of a chronic abscess.
   • Mobility Grade II or III.
   • Previously accessed or endodontically treated
   • Deep periodontal pockets more than 4 mm
   • Vertical root fractures, coronal perforation, calcification, and external or internal root resorptions.

4. Patients who could not interpret the NRS.

5. Patients with diabetes, immune-compromising, and immunosuppression disease and pregnant women were, also, excluded.