Triple blinded split mouth clinical trial after single visit root canal treatment to Compare Post-operative pain subsequent to different apical finishing sizes

Abstract Background This is a triple-blinded, prospective split-mouth clinical trial. It is important to shed light on the effect of different apical preparation sizes regarding postoperative pain within the same patient with the same pulpal histological status. The aim is to compare and evaluate the severity of postoperative pain following apical enlargement with two different sizes after the IBF using the visual analogue scale. Methods Fifty sides in twenty-five patients were assigned into two equal groups (25 per group) using E3 Azure rotary files; Group A was prepared two sizes greater than the IBF mesial canals, which were enlarged to 30#/.04 and 40#/.04 for the distal canals. Group B was prepared in three sizes larger than the IBF: 35#/.04 for mesial canals and 45#/.04 for the distal canals. On a VAS form, patients were questioned to indicate the degree of their pain and assisted in narrating their pain intensity during the following periods: 12, 24, and 72 hours, and after a week, also recorded by a second blinded clinician. VAS data were non-parametric and analyzed using the signed rank test for intergroup comparisons, Freidman's test, and the Nemenyi post hoc test for intragroup comparisons. Results showed that regardless of measurement time, enlargement of apical preparation was significantly associated with higher pain scores (p<0.001). Within both groups, there was a significant reduction of measured pain score with time, with values measured after 12 and 24 hours being significantly higher than values measured at other intervals (p<0.001) and with values measured after three days being significantly higher than 1-week value (p<0.001). Conclusion There is a relationship between postoperative pain and the size of the preparation. Trial registration number & date: NCT05847738, 08/05/2023.