CLINICAL
Irrigation in endodontics Drs. Peet J. van der Vyver and Heinrich Dippenaar explore activation devices for root canal irrigation solutions Irrigant agitation techniques and devices According to Gopikrishna, et al. (2014), the three most important characteristics for an endodontic irrigant are tissue dissolution, anti-microbicity, and the ability to remove the smear layer. Most irrigation protocols advocate the use of a combination of irrigation solutions such as NaOCl with EDTA or chlorhexidine (Gu, et al., 2009) to achieve this goal and to complement the shortcomings that are associated with the use of a single irrigant. According to Zehnder (2006), irrigants should be brought into direct contact with all canal wall surfaces for effective action, particularly for the apical portions of small root canal systems. Studies have indicated that after root canal preparation with nickel-titanium instruments, there are still untouched areas that can harbor tissue debris, microbes, and their byproducts (Peters, 2004; Schäfer, Zapke, 2000) (Figures 1 and 2), resulting in persistent periradicular inflammation (Naidorf, 1974). Different irrigant delivery systems and agitation systems for root canal irrigation have been proposed (Gu, et al., 2009). The systems can be divided into two broad categories: manual agitation techniques and machine-assisted agitation devices.
Manual agitation techniques Manual agitation techniques include: • Syringe irrigation with end-venting or side-venting needles • Brushes for debridement of the canal walls or for agitation of the irrigant inside the root canal (e.g., NaviTip® FX®, Ultradent Products Inc.) • Manual-dynamic agitation irrigation technique where apically fitting guttapercha cones are used in an up-anddown motion to activate the irrigation solution
Figure 1: Remnant of vital pulp tissue (white arrows) visible under 10x microscope magnification in the midroot area of a distobuccal root canal of a mandibular first molar, after root canal preparation with NiTi rotary instrumentation and sodium hypochlorite syringe irrigation with a side-vent needle
Machine-assisted agitation devices Machine-assisted agitation systems include: • Rotary brushes (e.g., canal brush operating at 600rpm in contra-angle handpiece to facilitate debris and smear layer removal) • Sonic irrigation devices (e.g., EndoActivator®, Dentsply Maillefer, Dentsply Tulsa Dental Specialties, and Vibringe®, Vibringe BV) • Ultrasonic irrigation devices (e.g., ProUltra PiezoFlow™, Dentsply Maillefer, Dentsply Tulsa Dental Specialties, and EndoUltra™, Vista™ Dental Products) • Pressure alternation devices (e.g., EndoVac, SybronEndo, and EndoSafe™, Vista Dental Products)
Passive irrigation Passive irrigation is achieved by slowly injecting an irrigation solution into the root canal system using different gauged and flexible cannulas (Figure 3). The smaller the cannula gauge, the deeper it can be placed into the root canal system. The cannula must fit loosely into the root canal to ensure reflux and coronal movement of the debris during
Dr. Peet J. van der Vyver is an extraordinary professor at the Department of Odontology, School of Dentistry, University of Pretoria, South Africa. He is in private practice limited to endodontics in Sandton, South Africa. (Visit www.studio4endo.com for more details.) Dr. Heinrich Dippenaar is guest lecturer at the Department of Odontology, School of Dentistry, University of Pretoria. He is a dentist in private practice, Welkom, South Africa.
22 Endodontic practice
Figure 2: Magnified cross-section view of a mesial root canal system in an extracted root canal-treated molar after preparation with rotary NiTi instruments, syringe irrigation with a side-vent needle using 17% EDTA and 3.5% sodium hypochlorite and warm vertical condensation. Note the remnants of debris not removed with conventional irrigation
Figure 3: Passive irrigation is achieved by slowly injecting an irrigation solution into the root canal system using different gauged and flexible cannulas
irrigation. If the operator slowly injects the solution in combination with continuous hand movements, it can potentially eliminate NaOCl accidents. The main limitation of passive irrigation is that a static reservoir of irrigant restricts the potential for any reagent to penetrate, circulate, and clean all aspects of root canal systems. Senia, et al. (1971), demonstrated that NaOCl does not extend any closer than 3 mm from working length during irrigation, even if the root apex is enlarged up to a size 30. The first reason is because of air entrapment by an advancing liquid front in closed-end micro-channels (Migun, Azuni, 1996; Migun, Shnip, 2002), called the vapor Volume 8 Number 1