Evaluation of Effect of Poloxamer on Smear Layer Removal Using Apical Negative Pressure: An In Vitro Scanning Electron Microscopy Study

Abstract Aims: The aim of this study was to assess the smear layer removal efficacy of sodium hypochlorite (NaOCl) and ethylene diamine tetraacetic acid (EDTA), with and without the addition of poloxamer, in an in vitro model. Materials and Methods: In this in vitro study, 60 human premolars were randomly selected and decoronated to standardize the root length to 15 mm. The working length was set 1 mm short of the apex. The canals were instrumented to size F3 using the Protaper file system, with irrigation using NaOCl and saline between instrumentations. The samples were randomly divided into four groups based on the final irrigation protocol: Group 1 ( n = 15) - 3% NaOCl with poloxamer, Group 2 ( n = 15) - 17% EDTA with poloxamer, Group 3 ( n = 15) - 3% NaOCl without poloxamer, and Group 4 ( n = 15) - 17% EDTA without poloxamer. All samples were irrigated using an apical negative pressure system, and smear layer removal was analyzed using scanning electron microscopy (SEM). A five-graded scoring system was used to assess smear layer removal. Data were statistically analyzed using the Kruskal–Wallis test. Results: The group irrigated with EDTA and poloxamer showed the most effective smear layer removal, with a median score of 2 in both the middle and apical thirds of the canal. The NaOCl with poloxamer group showed a median score of 3, while the NaOCl-only group had a median score of 5, indicating less efficient removal of the smear layer. Conclusion: The study concluded that the addition of poloxamer to NaOCl and EDTA improved smear layer removal by lowering the surface tension of the irrigants. The combination of EDTA with poloxamer exhibited the best smear layer removal, followed by NaOCl with poloxamer. The NaOCl-only group showed the least effectiveness. This enhanced smear layer removal improves irrigant penetration, particularly for NaOCl, and may also enhance its antimicrobial efficacy. Furthermore, poloxamer’s surfactant properties suggest its potential as a drug delivery agent for intracanal medicaments. The results suggest that incorporating poloxamer into root canal irrigation protocols can significantly improve the efficacy of smear layer removal, leading to better irrigation outcomes and improved penetration of medicaments. This could enhance the overall success of endodontic treatments, particularly by improving antimicrobial activity and facilitating more effective drug delivery to the root canal system. Future research could explore the long-term clinical effects of using poloxamer-enhanced irrigants in various root canal systems, as well as investigate its potential as a carrier for additional intracanal medicaments. Further studies should also examine the impact of poloxamer on the mechanical properties of the root canal dentin and its compatibility with other commonly used irrigants.