Effect of Vapor Lock on Root Canal Debridement by Using a Side-vented Needle for Positive-pressure Irrigant Delivery

Abstract

Introduction This study examined the effect of vapor lock on canal debridement efficacy by testing the null hypothesis that there is no difference between a “Closed” and an “Open” system design in smear layer and debris removal using a side-vented needle for irrigant delivery. Methods Roots in the “Closed System” were sealed with hot glue and embedded in polyvinylsiloxane to restrict fluid flow through the apical foramen during cleaning and shaping. For the “Open System”, the apical foramen was enlarged and connected to the external environment via a channel within the polyvinylsiloxane to permit unrestricted fluid flow. Smear and debris scores were evaluated using SEM and analyzed using Cochran-Mantel-Haenszel statistic. Results No difference in smear scores was detected between the two systems at all canal levels. Significant differences in debris scores between the two systems were found at each canal level: coronal (p<0.001), middle (p<0 .001) and apical (p<0.001). Conclusion The null hypothesis was rejected; presence of an apical vapor lock effect adversely affects debridement efficacy. Thus, studies with unspecified or questionable mechanisms to restrict fluid flow through the apical foramen have to be interpreted with caution.

Smear Layer Removal and Canal Cleanliness Using Different Irrigation Systems (EndoActivator, EndoVac, and Passive Ultrasonic Irrigation): Field Emission Scanning Electron Microscopic Evaluation in an In Vitro Study

“…An in vitro closed-end canal model was used because it more accurately simulates in vivo conditions such as gas entrapment in the root canal and periodontal ligament (14). The removal of the smear layer is usually accomplished by irrigants capable of dissolving both organic and inorganic components (17,23).…”

“…This is insufficient for complete cleaning of the complex anatomy of the root canal system (lateral canals, isthmuses, fins, and accessory canals) (13). A vapor lock that results in trapped air in the apical third of root canals has also been considered because it might hinder the exchange of irrigants and affect their debridement efficacy (14). Different devices for irrigation delivery have been proposed to increase the flow and distribution of irrigating solutions within the root canal system (15), especially at the apical third level.…”

Comparison of the Antibacterial Effect and Smear Layer Removal Using Photon-Initiated Photoacoustic Streaming Aided Irrigation Versus a Conventional Irrigation in Single-Rooted Canals: AnIn VitroStudy

“…25,26 Furthermore, hand needle irrigation alone was not able to create sufficient volume and flow of the irrigant in closed canal systems. 27 In the closed canal system, irrigant extrusion beyond 1-1.5 mm of the needle could have generated a liquid film along the air bubble-canal wall interface. Adequate irrigant replacement cannot be achieved in this area, resulting in gross debris retention.…”

“…Adequate irrigant replacement cannot be achieved in this area, resulting in gross debris retention. 27 It has been suggested that Er:YAG laser activated in a limited volume of fluid, the high absorption of the laser wavelength in water, combined with the high peak power derived from the short pulse duration, would have resulted in a photomechanical phenomenon. 11 This action may remove bacteria and smear layer in the root canal.…”

Measurement of temperature changes during cavitation generated by an erbium, chromium: Yttrium, scandium, gallium garnet laser

“…However, hand irrigation is not sufficiently effective in the apical third of the root canal, or in oval extensions, isthmuses, and anastomoses [2]. Vapour lock that results in trapped air in the apical third of the root canal may also hinder the exchange of irrigants and decrease the efficacy of debridement [3].…”