Antimicrobial Activities of ZnO NPs Against Oral Infection-Associated Pathogens: A Review of Activity Enhancement via Different Modifications.

Oral infections remain a significant global health concern and are primarily associated with pathogenic microorganisms that contribute to dental caries, periodontal diseases, endodontic infections, and oral candidiasis. The increasing prevalence of antimicrobial resistance and the limitations of conventional antimicrobial agents have stimulated the search for alternative therapeutic strategies. Zinc oxide NPs (ZnO NPs) have attracted considerable attention due to their broad-spectrum antimicrobial activity, biocompatibility, chemical stability, and cost-effectiveness. ZnO NPs exhibit potent antimicrobial effects against a wide range of oral pathogens through multiple mechanisms. Recent studies have demonstrated that the antimicrobial performance of ZnO NPs can be significantly enhanced through modifications such as particle size reduction, morphology control, metal doping, surface functionalization, and incorporation into composite materials. These modifications improve microbial interactions, increase surface reactivity, and enhance overall antimicrobial efficacy against oral infection-associated microorganisms. In this review, we comprehensively discuss the antimicrobial activities of ZnO NPs against microorganisms associated with oral infections. Particular emphasis is placed on the influence of various modification strategies, including size-dependent effects, metal-ion doping, polymer incorporation, and hybrid nanocomposite formation, on antimicrobial performance. The underlying mechanisms responsible for enhanced antimicrobial activity are also summarized. We hope that this review will provide a valuable resource for researchers and clinicians interested in the development of advanced ZnO NP-based antimicrobial materials for the prevention and treatment of oral infections.