There is some conflicting information about when children should start using fluoride toothpaste. Studies have suggested that young children who consume large amounts of fluoride through fluoridated water, beverages, and toothpaste have an increased chance of developing mild enamel fluorosis see http://blog.teethremoval.com/large-amounts-of-fluoride-consumed-by-young-children-leads-to-fluorosis/. Hence some felt that not using any fluoridated toothpaste when a child was young was the better choice, whereas some felt that that using a small amount of fluoride toothpaste was okay
In 2014, the ADA’s Council on Scientific Affairs updated its guidance on the use of fluoride toothpaste for children. The new guidance is that children’s teeth should be brushed with fluoride toothpaste as soon as the first tooth comes in. The idea is to provide children with the full benefit of cavity protection while also minimizing the risk of the development of fluorosis.
The ADA’s Council on Scientific Affairs based their guidance on a systematic review of the evidence. They feel a smear of toothpaste with fluoride for children under 3 and a pea size amount of toothpaste with fluoride for children 3 to 6 will help prevent cavities and is less likely to cause fluorosis. Furthermore, children should spit out any toothpaste as soon as they are able.
The previous guidance from ADA’s Council on Scientific Affairs was that water should be used to brush the teeth of children younger than 2 and that for children ages 2 to 6 a pea size amount of fluoride toothpaste should be used. The new guidelines are based on a review of scientific evidence.
Note I have also previously mentioned in a blog post fluoride in water you drink as a child effects your teeth in older age, see post http://blog.teethremoval.com/fluoride-in-water-at-birth-helps-dental-health-in-later-adult-life/.
Source: DrBicuspid. ADA: Use fluoride toothpaste when 1st tooth appears. February 13, 2014. http://www.drbicuspid.com/index.aspx?sec=log&URL=http%3a%2f%2fwww.drbicuspid.com%2findex.aspx%3fsec%3dnws%26sub%3dthd%26pag%3ddis%26itemId%3d315177.