The American Dental Association (ADA) recommends kids use toothpaste with fluoride to prevent cavities–and homemade toothpaste does not have fluoride. The ADA stresses the importance of kids using the correct amount of toothpaste to avoid ingesting too much (about the size of a grain of rice for kids under the age of 3 and for 3 to 6, a pea size dollop of toothpaste).