Photoresponsive Materials for Root Canal Infection Control: Mechanisms, Applications, and Clinical Challenges

Root canal infection remains difficult to control because of the complex anatomy of the root canal system and the increased tolerance of microbial biofilms to conventional disinfection. Photoresponsive materials have therefore emerged as potential adjuncts that use photodynamic or photothermal mechanisms. This review summarizes the mechanisms and applications of conventional photosensitizers, photothermal agents, nanodelivery systems, and multimodal photoresponsive platforms. Photodynamic materials generate reactive oxygen species (ROS) that induce oxidative damage, whereas photothermal materials convert light energy into localized heat to inactivate microorganisms and disrupt biofilm structure. Their antibacterial effects and complementary roles alongside mechanical preparation and chemical irrigation are critically evaluated. Current evidence suggests that photodynamic therapy may provide additional reductions in microbial load, whereas photothermal and multifunctional nanomaterial systems remain supported mainly by preclinical studies. Major challenges include limited light penetration, uneven material distribution, insufficient oxygen supply, thermal injury, material residues, and inconsistent treatment parameters. Future studies should improve biocompatibility, delivery, and removal; standardize experimental protocols; and evaluate clinically meaningful outcomes, including periapical healing, infection recurrence, and tooth survival.