Research progress on N-acetylcysteine in the prevention and treatment of oral infectious diseases

N-acetylcysteine (NAC) is an acetylated derivative of cysteine that exerts multiple biological activities, including antioxidant, anti-inflammatory, antimicrobial, and mucolytic effects, and has been widely used clinically for the treatment of respiratory diseases. NAC not only directly scavenges reactive oxygen and nitrogen species and strengthens endogenous antioxidant defenses by promoting glutathione synthesis but also modulates immune responses and suppresses inflammatory signaling pathways such as nuclear factor kappa B, thereby attenuating inflammation. In addition, NAC disrupts biofilm architecture by cleaving disulfide bonds, reduces microbial virulence, and enhances the penetration of antimicrobial agents, conferring robust antibacterial and antibiofilm activities. The initiation and progression of oral diseases—including dental caries, periodontal disease, pulpal-periapical disease, and infectious oral mucositis—are closely associated with pathogenic infection, oxidative stress, and dysregulated immune-inflammatory responses. NAC can inhibit Streptococcus mutans adhesion and biofilm formation, thereby reducing cariogenic virulence; mitigate periodontal tissue destruction through antimicrobial, anti-inflammatory, and antioxidant actions, and may modulate bone metabolism; enhance the clearance of Enterococcus faecalis biofilms and improve the efficacy of antimicrobial therapy; and inhibit the growth and hyphal formation of Candida albicans. Collectively, NAC is emerging as a promising agent for the prevention and treatment of oral infectious diseases. This review systematically summarizes the major bioactivities of NAC, its mechanistic actions in oral infectious diseases, and its therapeutic prospects, with the aim of providing a theoretical basis for future basic and clinical investigations.