Initially, you can simply use water on a soft-bristled toothbrush for your baby’s first few teeth. Once several teeth erupt, add a tiny amount of toothpaste (i.e. the size of a grain of rice). Continue to use this tiny amount of toothpaste for your toddler, up until about age 3. At this age, toddlers begin to understand the concept of spitting the toothpaste out. Toddlers 3 years and older can start to use a pea-sized amount of toothpaste.