Antimicrobial Effectiveness of Hydrodynamic and Conventional Rinsing in Root Canal

Objectives: Bacterial infection of the root canal is the principial cause of parodontitis apicalis. In order for endodontic therapy to be successful, the reduction or elimination of bacteria is still a major aim of endodontic preparation. The purpose of the in vitro study was to compare the effectiveness of the hydrodynamic and conventional rinse of root canals (RC) with NaOCl solution (2,5%) and chlorhexidine (CHX, 1%). Methods: 20 RCs of freshly extracted caries free teeth were prepared by crown down technique (K3, Kerr). The teeth were set up in silicone (Flexitime/Heraeus/Kulzer), plasma sterilized and stored in a moistened chamber for 5 days at 35 ± 2 °C. Than the RCs were inoculated with 0.05 ml of standardized suspensions of Enterococcus faecalis (mean cfu 2,0 x 107; cfu = colony forming units). After incubation of teeth for 48 h at 35 ± 2 °C (Heraeus VT 5042EK/N2) and rinsing procedures (RinsEndo/Dürr, NaOCl: n = 5, CHX: n = 5; conventional rinsing NaOCl: n = 5, CHX: n = 5) the counts of E. faecalis were determined by sampling root canals with sterile paper points (ISO30, VDW). The paper points were diluted in 1 ml NaCl up to 10-8. 0.1ml of each dilution was plated threefold on mitis salivarius agar (Difco). After anaerobic incubation of 7 days at 35 ± 2 °C the cfu of E. faecalis was counted. Results: E. faecalis was established in the root canals before treatment with a mean cfu of 1.5 x 104. Only in root canals after conventional treatment with CHX, E. faecalis could survive with a mean cfu of 0.3 x 102. Conclusion: Further studies have to show the superiority of the hydrodynamic rinse of root canals in comparison to conventional methods.