In this clinical trial study, 48 patients with average age of 25-50 years who were medically healthy were selected. The study was done on vital anterior single root canal teeth with severe decay and spontaneous pain at range of 0-30 in visual analogue scale (VAS) but without periapical lesion (radiographically), swelling, or fistula. The patients were allocated into three groups matched for sex to receive 400 mg Ibuprofen (Aria, Tehran, Iran), 200 mg Sulindac (Merksharp & dohm, USA) or placebo one capsule as prophylaxis 1 hour before treatment. The drugs were prepared identically as capsules. All patients will receive standard treatments with identical method. In addition, the patients were given two acetaminophen codeine 300/10 mg tablets for severe continuous post-operative pain. Intensity of pain is recorded by the patients through Visual Analogue Scale 6, 12, 24, 48, and 72 hours after treatment.