Preventive dental materials are tools and products used to prevent cavities and tooth decay, including sealants, fluoride toothpastes and mouthwashes, and they work by strengthening enamel, reducing acid in the mouth, and preventing bacteria that cause decay. The group presented on different types of preventive materials like sealants, toothpastes, and mouthwashes, explaining what they are, how they work, and their functions and ideal requirements.