To measure the Effect of Rosmarinus Officinalis versus 2.5%Sodium Hypochlorite as Root canal Irrigants on the Intensity of post-operative pain and Bacterial Reduction in asymptomatic necrotic Mandibular premolars.

Inclusion Criteria:

1. Systematically healthy patient (ASA I and II).

2. Age between 20 and 45 years with no sex predilection

3. Mandibular permanent premolar teeth:

   • Diagnosed clinically with pulp necrosis.
   • Absence of spontaneous pain.
   • Radiographic evidence of root and root canal.
   • Slight widening in the periodontal membrane space or with periapical radiolucency.
   • No response to cold pulp tester (ethyl chloride spray)

4. Patients who can understand and interpret Numerical rating scale (NRS).

5. Patients' acceptance to participate in the trial

Exclusion Criteria:

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

  2- History of intolerance to NSAIDS. 3- If analgesics or antibiotics have been administrated by the patient during the past 24 hours preoperatively as it might alter their pain perception.

  4- Pregnant women: Avoid radiation exposure, anesthesia, and medication. 5- Teeth with: i. Vital teeth. ii. Double canal mandibular premolar teeth iii. Association with swelling or fistulous tract. iv. Acute peri-apical abscess and swelling: Need special treatment steps which could involve additional visits with incision and drainage. Also, it could influence initiation and progression of postoperative pain.

  v. Mobility Grade II or III. vi. Pocket depth more than 5mm. vii. Previous root canal therapy. viii. Non-restorable teeth: Hopeless tooth

• Immature teeth.

• Radiographic evidence of external or internal root resorption vertical root fracture, perforation, calcification.

Triple (Participant , Investigator, Outcomes assessor