The aim of this study to assess effect of ketorolac premedication on the effectiveness of the inferior alveolar nerve block, pretreatment and postoperative pain in patients with symptomatic irreversible pulpitis.

• Patients will be clinically and radiographically examined and their eligibility will be assessed and preoperative pain will be measured. Eligible patients will be treated in one visit.
• Patients will be randomly assigned to one of 2 groups: experimental group (taking a 10 mg tablet of ketorolac) and the control group (taking a placebo tablet). Each tablet will be taken one hour before starting treatment. The patient's pain will be assessed before local anesthetic adminstration. After 15 minutes of the initial inferior alveolar nerve block (IANB), the teeth will be examined using a cold pulp sensitivity test; in case of no or mild pain, the treatment will be initiated.
• During root canal treatment, no to mild pain response will be considered success. In case of failure, supplemental anesthesia will be administrated.
• Postoperative pain will be assessed 6, 12, 24 and 48 hours after treatment. The number of patients who will require rescue analgesic medication within the 48 hours postoperatively will be counted.

Inclusion Criteria:

1. Age between 18-45 years old.
2. Males or Females.
3. Mandibular Posterior teeth with symptomatic irreversible pulpitis.
4. Patients with non-contributory systemic condition.

Exclusion Criteria:

1. Patients allergic to any analgesics or antibiotics or anesthetics
2. Pregnant females
3. If analgesics have been administrated during the past 8 hours before endodontic treatment.
4. Irrestorable teeth.