MgO nanoparticles have been recently discovered as an antibacterial, however, they limited by property degradation due to agglomeration. The addition of a coating agent, such as a zein polymer, is effective in preventing agglomeration without affecting nanosized properties. The aim of this study was to assess the antimicrobial property of MgO nanoparticles when coated with a zein polymer against several oral bacteria and fungi. This was done by utilizing various assessment techniques. The ultimate aim is to use these nanoparticles in dental preparations. The antimicrobial activity of zein-coated MgO nanoparticles at different concentrations of 0.5, 1 and 2% were tested against four different microorganisms: Staphylococcus aureus, Streptococcus mutans and Enterococcus faecalis (gram positive bacteria), and Candida albicans (as oral fungus). Two different techniques were utilized: the Kirby-Bauer test, and a modified direct contact test. The results indicated that the antibacterial effect of 1% or 2% zein-coated MgO nanowires were statistically significant (p<0.05) against the four organisms studied: S. mutans, S. aureus, E. faecalis and C. albicans. Zein-coated MgO nanoparticles are a new human friendly and potent antimicrobial agent that can be incorporated in the formulation of a variety of new dental materials and products that should provide improvements in dental care and oral health.