A comparative evaluation of efficacy of smear layer removal using a novel handpiece mounted continuous irrigation system – an in vitro stereomicroscopic study

Authors: Sneha Chandran, Elsy P Simon, Mohammed Ashik, Nimmy Kurian

DOI: 10.18231/j.ijce.11444.1758947709

Keywords: continuous irrigation system ,smear layer, sodium hypochlorite

Abstract: Aim and objective: To compare and evaluate the efficacy of smear layer removal using a novel handpiece mounted continuous irrigation system with simultaneous root canal preparation from the apical third of root canals. Introduction: During canal preparation, dentine chips created by the action of endodontic instruments add to the remnants of organic material and irrigating solutions, forming a smear layer that adheres to the canal walls. Syringe irrigation is the most commonly used irrigation method. The exchange of irrigant apical to the needle tip is dependent on the needle type, design, and gauge and it is usually limited to 1 to 1.5 mm beyond the needle tip, which depicts that its effectiveness is limited by its depth of insertion. Therefore, to deliver active irrigant apically, the needle is required to be inserted near the working length (WL). There is only a limited active irrigant available at the apical area when intermittent irrigation with syringe irrigation is used. In the current in vitro study, we used an innovative method of simultaneous (or continuous) irrigation during root canal preparation in roots with sealed apices.The present research focuses on the smear layer removal efficacy of handpiece mounted continuous irrigation system with simultaneous root canal preparation compared with conventional syringe irrigation from the apical third. Material and Methods: An in vitro study was conducted using 10 extracted human premolars, randomly divided into two groups: Group 1: Continuous irrigation with 3% sodium hypochlorite (NaOCl) manually delivered at 1 ml/min through a novel handpiece-mounted system during rotary instrumentation. Group 2: Conventional syringe irrigation using 2 ml of 3% NaOCl between each rotary file, delivered via a side-vented 5 ml syringe. All teeth were instrumented to size 30/06 taper, stained with 1% methylene blue dye, sectioned longitudinally, and observed under a stereomicroscope at 40× magnification. The depth of dye penetration in the apical third was assessed as an indirect measure of smear layer removal. Result: Group 1 demonstrated greater dye penetration in the apical third compared to Group 2, indicating more effective smear layer removal. The continuous replenishment of irrigant during instrumentation may have enhanced cleaning efficiency by minimizing debris compaction and improving irrigant contact with canal walls. Conclusion: Within the limitations of this study, the handpiece-mounted continuous irrigation system showed superior smear layer removal in the apical third compared to syringe irrigation. This technique may enhance the cleaning efficacy of endodontic procedures, although further studies are needed to address practical limitations such as manual delivery control, operator dependency, and clinical implementation challenges.