Instrumentation kinematics does not affect bacterial reduction, post‐operative pain, and flare‐ups: A randomized clinical trial

Aim This randomized clinical trial aimed to assess the effect of instrumentation kinematics (reciprocation or continuous rotation) on bacterial reduction, post‐operative pain, and incidence of flare‐ups after root canal treatment of single‐rooted mandibular premolars with asymptomatic apical periodontitis. Methodology Sixty‐six patients were included in this prospective, parallel, randomized clinical trial. Patients were randomly allocated into two groups (N = 33) according to the kinematics of the shaping instrument: WaveOne Gold (WO) used in reciprocation or One Shape (OS) used in continuous rotation. Under complete asepsis, bacterial samples were taken before (S1) and after (S2) a standard cleaning and shaping protocol. Evaluation of bacterial reduction was done by both culture technique and quantitative real‐time polymerase chain reaction (qPCR) analysis. Post‐operative pain was evaluated using the visual analogue scale (VAS) after 24, 48, and 72 h following treatment, while flare‐ups were recorded as a binary outcome (Yes/No). Independent and paired t‐tests were used for inter‐ and intra‐group comparisons for bacterial count data, respectively. For post‐operative pain score, inter‐group comparisons were analyzed using the Mann–Whitney U‐test while intra‐group comparisons were analyzed using Friedman test followed by pairwise comparisons utilizing the Wilcoxon signed rank test with Bonferroni correction. The significance level was set at p ≤ .05 within all tests. Results All the allocated participants received the intervention and were analysed. The comparison between culture and qPCR methods showed that qPCR analysis demonstrated significantly higher pre‐instrumentation baseline bacterial count (p