Bubble engineering in endodontic irrigation: Emerging roles of microbubbles and nanobubbles in root canal disinfection – A narrative review

Abstract

Complete disinfection of the root canal system remains difficult because irrigants may not adequately reach anatomical complexities, dentinal tubules, and microorganisms protected within biofilms. Recent advances in fluid engineering have introduced microbubbles and nanobubbles as potential means of improving irrigant delivery and antimicrobial action. This narrative review examines the scientific basis and current evidence for the use of engineered bubbles in endodontic irrigation. Relevant literature was identified from PubMed/MEDLINE, Scopus, and Google Scholar using combinations of terms related to microbubbles, nanobubbles, root canal irrigation, biofilms, cavitation, and irrigant activation. Studies directly addressing endodontic applications were prioritized, supplemented by relevant mechanistic evidence when necessary. Microbubbles can oscillate and undergo activation-associated cavitation, generating fluid motion and mechanical forces that may facilitate biofilm disruption and irrigant exchange. Nanobubbles display distinctive interfacial behavior and persistence in liquids and have been investigated for enhancing antimicrobial delivery, dentinal penetration, and smear-layer removal. Experimental studies have further explored their combination with ultrasonic, photodynamic, and laser-based activation. Despite encouraging findings, the evidence is largely derived from laboratory investigations, and considerable variation exists in bubble composition, generation, and activation protocols. Engineered bubbles may provide a new physicochemical dimension to root canal irrigation; however, standardized experimental models and clinical studies are required to determine whether these advantages translate into improved treatment outcomes.