My thesis aims to raise awareness of the potentially harmful effects of nanoparticles (NPs) used in dentistry. I will present nanoparticles, their properties, how they are used in dentistry, and the hazards they create. The NPs can be harmful, both to the human body and to the environment, and can therefore be defined as hazardous waste. The use of NPs in dental practice has been increasing in recent years. Because of their small size and surface properties, they can cross barriers such as mucous membranes and the brain-blood barrier. The exposure to NPs in dental practice is thus a concern. Dental healthcare workers should therefore be aware of these potential hazards.