What leeuwenhoek discover by looking at the plaque from his own teeth?

Anton van Leeuwenhoek discovered tiny living microorganisms, which he referred to as "animalcules," when he examined dental plaque from his own teeth. This observation marked the first documented instance of microorganisms being viewed under a microscope. His findings contributed significantly to the field of microbiology, revealing the existence of a vast, previously unseen world of bacteria and other small life forms. Leeuwenhoek's work laid the foundation for the understanding of microbial life and its implications for health and disease.