Magnesium is one of the bioelements necessary for proper human functioning. It is classified as a macronutrient. Together with calcium and phosphorus, it is the main building component of teeth. It has antibacterial properties, as consequence of which it can impede the formation of biofilm and thus reduce inflammation caused by bacterial toxins. Along with calcium, phosphorus and vitamins, magnesium helps maintain the health of the human body. The scientific literature contains an increasing number of studies describing new methods for preventing caries resulting from interference with the oral microbiome. Modification of the microbiome and the use of prebiotics may prove to be groundbreaking. Magnesium may have the potential to function as a prebiotic because it promotes the colonization of commensal streptococci in the oral cavity. By changing the oral microbiome, it could play an important role in dental caries prevention. Nanotechnology is a new concept of material production that has emerged both in dentistry and other fields. In view of the resistance of certain bacteria to antibiotics and other bactericidal agents, alternative dental materials with increased antibacterial properties are being sought by adding antibacterial nanoparticles (NP) to their composition. One of the most commonly used metal oxides is magnesium oxide. Its antibacterial action involves disrupting the bacterial cell membrane. It seems that nanoparticles may be promising fillers for dental composites. However, due to the limited character of the clinical trials to date, there is a need for further experiments.