The document discusses the different parts of teeth including the crown, enamel, dentin, and pulp. It describes the four types of teeth - incisors for cutting, canines for tearing, premolars for crushing, and molars for grinding and swallowing food. Cavities are caused by plaque bacteria that leads to tooth decay if not removed by brushing and flossing. Maintaining good oral hygiene helps prevent cavities and keeps teeth healthy.