Development of a smart root canal sealer capable of releasing antimicrobial agents in response to pH changes

Abstract

Persistent microbial infection remains one of the primary causes of endodontic treatment failure despite advances in root canal instrumentation and irrigation. Conventional root canal sealers provide mechanical sealing but possess limited long-term antimicrobial activity, reducing their effectiveness against residual bacteria and recurrent biofilm formation. The development of smart root canal sealers capable of releasing antimicrobial agents in response to localized pH changes represents a promising strategy for improving treatment outcomes. These stimuli-responsive materials remain relatively inactive under physiological conditions but selectively release therapeutic agents in the acidic environment associated with bacterial metabolism and infection. Such controlled drug delivery enhances antimicrobial efficacy while minimizing unnecessary exposure to antimicrobial compounds, reducing cytotoxicity, and preserving the surrounding periapical tissues. Advances in nanotechnology, bioceramic materials, and pH-sensitive polymers have enabled the fabrication of multifunctional sealers with improved sealing ability, bioactivity, biocompatibility, and sustained antimicrobial performance. This review discusses the principles, design strategies, biomaterial components, drug-release mechanisms, biological performance, clinical applications, current challenges, and future directions of smart pH-responsive root canal sealers. The integration of responsive biomaterials with targeted antimicrobial delivery offers a significant step toward next-generation endodontic materials capable of enhancing disinfection, promoting tissue healing, and improving the long-term success of root canal therapy.