Influence of Ultrasonic Activation of Endodontic Irrigants on Microbial Reduction and Postoperative Pain: A Scoping Review of In Vivo Studies

Objective: Root canal irrigation plays a critical role in achieving effective chemomechanical disinfection during endodontic therapy. Conventional syringe irrigation, typically using sodium hypochlorite, ethylenediaminetetraacetic acid, and chlorhexidine, is limited by its delivery method and often fails to adequately penetrate complex canal anatomies, compromising disinfection. Advancements such as ultrasonic and multisonic irrigation systems aim to address these limitations. This scoping review compares the clinical effectiveness of ultrasonic irrigation techniques with conventional syringe irrigation, focusing exclusively on in vivo studies conducted within the oral environment. Methods: A comprehensive scoping review was conducted using PubMed, Scopus, Dentistry & Oral Sciences Source, and Google Scholar. Peer-reviewed, full-text articles published in English between 2015 and 2025 were screened by four independent reviewers based on predefined inclusion and exclusion criteria. Eligible studies were thematically analyzed. Results: Of 312 records screened, eleven studies met the inclusion criteria. Ultrasonic irrigation was associated with improved clinical outcomes, particularly greater reductions in bacterial load and endotoxins; however, findings regarding its effect on postoperative pain were inconsistent, with some studies reporting a benefit while others observed no significant difference. These outcomes were attributed to mechanisms such as acoustic streaming and cavitation, which enhance irrigant penetration, promote fluid dynamics, and facilitate debridement in anatomically complex regions. Conclusions: Ultrasonic irrigation appears to hold promise for enhancing the efficacy and efficiency of root canal treatment. Existing in vivo studies suggest potential clinical advantages over conventional syringe irrigation, underscoring the need for further high-quality clinical research to more definitively establish its benefits.