IRCT20190331043142N1 IRCT 2019-04-18 Shahid Beheshti University of Medical Sciences Effect of the number of treatment visits on the outcome of root canal therapy Comparison of outcomes of single- versus multiple-visit in endodontically treated anterior and premolar teeth, using Cone-beam Computed Tomography 2019-01-21 anticipated 26 Complete https://irct.ir/trial/38615 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Restricted randomization and specifically random allocation rule was utilized in order to make the sample size in both groups equal. The whole sample size had been determined in advance (n=30) and was divided equally between two groups. Fifteen cards coded 1 and 15 others cards coded 2 were placed in an opaque bowl. A person blinded to the study picked a card from this bowl for each patient, Blinding description: The clinician could not be blinded to the procedure. Two calibrated clinicians other than the practitioner who performed the procedure would further analyze the size of the lesion in CBCT images. The statistician will be also blinded. 3 Condition 1: Chronic apical periodontitis. Condition 2: Periapical abscess with sinus tract. Condition 3: Periapical abscess without sinus. Intervention 1: Intervention group: Using calcium hydroxide as intra-canal medicament for 1 week and performing the root canal therapy in two visits. Intervention 2: Control group: Performing the root canal treatment in a single visit with no calcium hydroxide dressing. No - There is not a plan to make this available Justification or reason for not sharing IPD is Currently, we cannot publish individual patient data because of the need for further studies and analyses.