Some scholars have shown that metal nanoparticles have excellent antibacterial properties and can be used as a new type of antibacterial agent. In recent years, with the in-depth research on nanomaterials, its applications in the medical field have gradually increased. The oral cavity has a unique anatomical structure, and for oral infections, the current clinically commonly used treatment measures are oral or topical antibiotics. However, due to bacterial resistance and the special structure of dental plaque, the effect of antibiotics is not ideal. Metal and metal oxide nanoparticles have become the research hotspot of new antibacterial materials due to their small particles, large specific surface area, physical, mechanical, and chemical properties, and antibacterial properties. This article describes the antibacterial effect, antibacterial mechanism, biological toxicity, and application progress of metal nanomaterials in the oral cavity.