The purpose of this randomized clinical trial was to evaluate the incidence of postoperative pain after retreatment using different techniques. Patients whom need retreatment were included. The presence of postoperative pain was assessed after retreatment cases at 1, 6, 12, 24 and 48 hrs.

The aim of this clinical study was to evaluate the intensity and duration of postoperative pain after single-visit and multiple-visit root canal retreatment procedures. Patients who have asymptomatic failed endodontically treated teeth were included in this study and routine channel treatment procedure will be applied to these teeth. All of the patients have been recruited from the Istanbul Medipol University Dental Clinics in Istanbul. Eighty asymptomatic teeth were randomly participated into four treatment groups in terms of intracanal medicament applied. The presence of postoperative pain was assessed after 1, 6, 12, 24 and 48 hrs. Postoperative pain was recorded by each patient by using visual analogue pain scale. Before the retreatments, the nature of the study, complications and associated risks were totally explained and written informed consent was obtained from all study participants. The patients were offered local anesthetic before the treatment start. The routine root canal retreatment procedure was applied. Different intracanal medicaments used between sessions in accordance to the manufacturers' instructions. At the end of retreatment, each patient was given an evaluation sheet, explained the treatment procedure and using of visual analogue pain scales, and informed to be returned during the following one week. After one week the teeth was examined according to for pain intensity, percussion & palpation sensitivity, swelling, analgesic intake and clinical status.

Inclusion Criteria:

Patients who were not included the study who;

• were pregnant or breast feeding during the duration of the study,
• have systemic disease,
• have any pain and/or any facial swelling, abscess,
• were immunocompromised,
• were under 18 yrs. and over 65 yrs. age,
• were taking antibiotics or corticosteroids within previous three months,
• have multiple teeth that required retreatment at the same time period; for eliminating pain referral,
• have root canals that could not be well-treated with orthograde retreatment.

Exclusion Criteria:

The patients who forgot to fill out the form and took antibiotics and/or analgesics right after the first appointment of the therapy were excluded from the study.

The patients were unaware as to which study group they had been allocated.