The Effect of Time on the Antimicrobial Action of Passive Ultrasonic Irrigation, an In-Vivo Study

Abstract

Endodontic treatment aims to remove pulpal tissue, bacteria and their byproducts from root canals. However, this is difficult to achieve 100% in most cases. Studies have shown that ultrasonic irrigation reduces bacteria in the canals through destruction of bacterial cell wall. However, it has been suggested that its effect may be only transient. This research aims to study the antimicrobial effect of passive ultrasonic irrigation on the microbial flora of root canals over time, and to observe the antibacterial action of passive ultrasonic irrigation. Twenty five selected teeth in different patients were divided into four groups according to irrigation method, Group 1: received irrigation with passive ultrasonic irrigation (PUI) and sodium hypochlorite (NaOCl), Group 2: were irrigated with PUI and saline, Group 3: were irrigated with NaOCl by needle irrigation, and Group 4: irrigated with saline by needle irrigation. Five microbial samples were taken from each root canal at different time intervals and bacterial counts were compared between the samples. Statistical analysis showed no difference in the bacterial counts immediately and after 10 minutes; however the counts increased after 24 hours, suggesting that the antimicrobial action of passive ultrasonic irrigation may not be affected by time. Intra- and inter-group analysis showed no difference between passive ultrasonic activation of NaOCl over syringe application of the irrigant.