Multispecies biofilm removal by a multisonic irrigation system in mandibular molars

AIM: The aim of the study was to assess biofilm removal efficacy of GentleWave System and passive ultrasonic irrigation (PUI). METHODOLOGY: Twenty‐two human mandibular molars with Vertucci's type II configuration in the mesial root were selected. Teeth were autoclaved, inoculated with dental plaque and incubated in a CDC biofilm reactor for two weeks. The mesial roots were instrumented up to 20.06 file (V‐Taper) for the GentleWave group and up to 35.04 file (Vortex Blue) for PUI group. Irrigation was performed using GentleWave and PUI irrigation protocols (n = 11). Dentine debris on paper points samples were obtained for quantitative real‐time polymerase chain reaction (qPCR) and 16S ribosomal RNA gene sequencing (next‐generation aequencing—NGS). For qPCR, a non‐parametric test (α = 0.05) was used. Next‐generation sequencing data were analysed using mothur, with alpha diversity calculated as the Shannon and Chao1 indices and Bray–Curtis dissimilarities were used for beta diversity. Differences in alpha diversity and abundances of genera were evaluated using Kruskal–Wallis test. Differences in community composition were evaluated using analysis of similarity with Bonferroni correction for multiple comparisons. RESULTS: Quantitative real‐time polymerase chain reaction results showed that the reduction estimated in percentages for both groups was equivalent (p > .05). NGS analysis showed that both techniques promoted a significant reduction in reads and OTUs number (p < .05). Shannon alpha diversity and Chao1 index showed no differences between pre‐ or post‐treatment samples for both groups (p > .05). Additionally, pre‐treatment communities differed from post‐treatment samples in both groups regarding bacterial taxa reduction (ANOSIM R = 0.50 and 0.55, p < .001). CONCLUSIONS: Bacterial reduction in mesial roots of mandibular molars prepared to 35.04 with PUI was similar to those prepared to 20.06 with a multisonic irrigant activation system.