Influence of Needle Design and Irrigant Flow Rate on the Removal of Enterococcus faecalis Biofilms In Vitro

Abstract

This study aimed to evaluate the influence of needle design and irrigant flow rate on the removal of Enterococcus faecalis mature biofilms during sodium hypochlorite irrigation. Forty-eight single-rooted human teeth were instrumented (ProTaper F3), autoclaved and inoculated with Enterococcus faecalis to establish a two-week-old biofilm. E. faecalis biofilms were treated with Sodium hypochlorite that was injected in the root canals using three types of needles (NaviTip, ProRinse, IrriFlex). For the IrriFlex needle, one, two, or four bars of pressure was applied to the irrigating solution to increase flow rates. Bacteria were labeled with the LIVE/DEAD BacLight Bacterial Viability kit, and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α = 0.05). Bacterial viability was significantly reduced after sodium hypochlorite passive irrigation but the number of viable bacteria retrieved from root canal specimens irrigated with the Pro-Rinse needle was significantly higher compared to NaviTip and IrriFlex needles (p < 0.05). When the irrigant flow rate was increased, the viability of bacterial biofilms was significantly reduced compared to passive irrigation using the IrriFlex needle (p < 0.05). Applying higher flow rates during irrigation using the IrriFlex needle did not further reduce bacterial viability.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study

“…The lack of difference in canal decontamination after using ProDesign Logic 2 with different tapers, despite differences in the shape of the canal, suggests the possibility that the unprepared areas of the canal were decontaminated by NaOCl (Ordinola-Zapata et al, 2012). The use of a standardized irrigant flow rate of 5 mL/min (Boutsioukis et al, 2007), a total irrigant volume of 15 mL per root canal and a 30-G NaviTip needle (Ultradent Products Inc., USA) during preparation of the apical third (Provoost et al, 2022) placed up to 2 mm short of the WL may have promoted better penetration of 2.5% NaOCl in this area (Boutsioukis et al, 2010), allowing it to effectively act against the E. faecalis and C. albicans strains (Fidalgo et al, 2010;Gulsahi et al, 2014).…”

“…However, the interaction of these microorganisms may vary in different environments, such as root canals or the gut, and is a dynamic process. It is possible that the biofilm microenvironment within root canals has a positive influence on their ability to coexist and take advantage of the dentinal tubules (Ran et al, 2015). Understanding the pathogenic mechanisms of the species and its interrelationships may contribute to the effective clinical management of long-term infections.…”

Three-Dimensional Printed Teeth in Endodontics: A New Protocol for Microcomputed Tomography Studies

“…The Irriflex ® needle used is a polyethylene flexible needle that has a smoother progression inside the canal and does not wedge against root canal walls. It presents two side openings that produce two jets oriented in the direction of the root canal walls and delivers a large volume of irrigant at a high flow rate with a clinically minimal risk of apical extrusion [31]. However, for the SMRP to be effective, the irrigation must be carried out at high pressure and with the needle tip as close to the apex as possible for irrigant extrusion to occur.…”

Smear layer removal efficacy of irrigating solutions applied distinct needle designs: a scanning electron microscopy study

“…Side-vented needles (SVNs) have been developed to deliver the irrigation solutions laterally. Since these needles are designed with closed-ends, the possibility of irrigation solutions to overflow to the periapical region is also reduced [15]. The irrigation process applied with SVNs is expected to provide more efficacy compared to open-ended needles (OENs) [15][16][17].…”