Your child's teeth begin forming in the womb, so teething can begin when an infant's only months old. First teeth have made appearances as early as 4 months, but it's more common for them to come in between six and ten months of age. Your child should have all 20 of his or her baby teeth by age two or three. As soon as teeth appear, make brushing and flossing after meals a daily routine. Studies have shown brushing with a fluoride toothpaste helps children's first teeth grow healthy and strong. These baby teeth hold spaces for the permanent teeth, helping them grow into the correct alignment. There's little clinical evidence that sucking pacifiers or thumbs before permanent teeth come in will negatively affect the position of permanent teeth. Healthy teeth play an important role in speech and digestion, so it's a good idea to foster habits to promote oral hygiene.