Efficacy of Biofilm Removal in Root Canals Using a Polyamide Tip Oscillating with a Frequency in kHz

Background: This study aimed to verify the effectiveness of polyamide tips oscillating with a frequency in the kHz range in removing intraradicular biofilms formed in vivo. Materials and Methods: An intracanal biofilm model was established using the mandibular first molar of 10-week-old male Wistar rats to compare the efficacy of a polyamide tip oscillating with a frequency in kHz (EDDY) in removing biofilms from the root canal. Biofilm removal efficacy was compared between the following groups: EDDY, conventional needle irrigation (CNI), without irrigation (positive control), and no root canal treatment (negative control). The biofilm removal efficacy was investigated using scanning electron microscopy (SEM) of the root canal wall and quantitative polymerase chain reaction for the statistical evaluation of the number of bacteria in each group. Results: SEM of the root canal wall in the CNI and positive control groups showed multi-layered biofilms, whereas the EDDY group showed less or no biofilms at the opening of the dentinal tubules in the root canal wall. Quantitative analysis showed the EDDY group had statistically significantly lower bacterial counts than the positive control group, with no difference when compared to the negative control group. Although the EDDY group had fewer bacteria remaining than the CNI group, the difference was not statistically significant. Conclusion: A polyamide tip oscillating with a frequency in the kHz range, such as EDDY, is an effective strategy for biofilm removal from the root canal, not only by agitating the irrigant but also by mechanical action on the root canal wall