Biological, Radiographic and Clinical Evaluation of Various Inter-Visit Root Canal Dressings in Retreatment Cases: A Randomized Controlled Clinical Trial

Sixty patients presenting with failed root canal treated lower first molars with periapical lesion were included in this randomized controlled single-center clinical superiority trial with two parallel arms and randomly allocated to 3 equal groups (n = 20) according to the type of ICM used. Patients were randomly allocated to receive either Ca(OH)2 slurry that was prepared from pure Ca(OH)2 powder mixed with 3% NaOCl, calcium-silicate (Bio-C Temp) or calcium hydroxide (CH) as ICM. Teeth were instrumented using a rotary file system (M3 pro Gold) and irrigated with 3% NaOCl. Subsequently, the root canals were dressed with a Ca(OH)2 + NaOCl or calcium silicate (test groups) or Ca(OH)2 (control group). Periapical fluid samples were collected after accessing the root canal in the first visit and after the root canal dressing removal in the second visit 2 weeks later using paper point. Samples were transferred to the microbiology lab immediately and levels of pro-inflammatory marker (IL1B) were measured using a specific enzyme-linked immunosorbent assay (ELISA) immediately after the second visit to test the reduction in inflammatory marker level after intracanal medication usage. Also, preoperative and 12 months-postoperative radiographic evaluation by CBCT were obtained to measure volumetric reduction in lesion size using segmentation technique. And patients rated their pain pre-operatively and then after 6, 12, 24, 48, 72 h and 7 days using the VAS score. Clinical and radiographic follow-up evaluations were scheduled for 1 week, 1 month, 6 months and 12 months by examining the patient clinically using palpation and percussion tests and pain questionnaire and periapical digital radiographs to compare reduction in lesion size.