Evaluation of antimicrobial effect of different irrigation solutions used in root canal retreatment

Introduction and Aim: This in vivo study aims to evaluate the effect of the use of different irrigation solutions and the activation of these solutions on microbial change in root canals which are bound for root canal retreatment. Material and Method: Forty patients with single-root and single-canal, root canal-treated mandibular premolar teeth with apical periodontitis were selected for this study. In line with the final irrigation regimens used during root canal retreatment, patients were divided into 4 groups with a computer software: Group I: 17% EDTA+ 2.5% NaOCl, Group 2: 2.5% NaOCl/ 9% HEBP (Medcem, Vienna, Austria), Group 3: 17% EDTA + 2.5% NaOCl + EA, Group 4: 2.5% NaOCl / 9% HEBP + EA. Bacteriological samples were taken from the root canal before chemomechanical preparation (S1) and after final irrigation (S2) at the first appointment, and after the removal of intracanal medicament (S3) and after final irrigation (S4) at the second appointment. The total number of bacteria was measured by microbiological culture method in the samples taken. Differences between groups in statistical analyses from culture method data were measured by Kruskal Wallis test, intra-group comparisons by Friedman test, and percentile reduction levels of bacterial numbers in bilateral comparisons between groups by Mann Whitney U test. The results were evaluated at P< 0.05 significance level Results: For intra-group comparisons, the amount of decrease in bacteria numbers for S1 and S2 samples in all groups is statistically significant (p<0.05). No statistically significant difference was observed in intergroup comparisons of bacterial reduction amounts in S1-S2 samples (p> 0.05). Regarding intra-group comparisons, there were no statistically significant differences between the number of bacteria for S2-S3 samples in Group II and Group IV (p> 0.05), while significant differences were observed in Group I and Group III (p< 0.05). For intra-group comparisons, the number of bacteria between S3-S4 samples in all groups decreased in a statistically significant way (p <0.05). With regard to quantitative comparison between groups, it was found that there was no statistically significant difference between the percentage decreases in bacteria numbers between S3-S4 samples (p> 0.05). Conclusion:. All irrigation solutions used in the disinfection of teeth diagnosed with apical periodontitis were found to be effective in reducing the microbial load in the canal. Irrigation solutions, conventional syringe irrigation and sonic activation by EA showed a similar effect in reducing the number of bacteria in the main root canal. Key words: EA, HEBP, Conventional syringe irrigation, Retreatment.