It is well known that fluoride deficiency causes tooth decay, and that tooth decay is the most common disease on the planet. However, most people still do not think of themselves as fluoride deficient, even when they have rampant tooth decay. Most people think of fluoride as something that is put on the surface of teeth to help prevent tooth decay. This (fluoride toothpastes, rinses, dental office dips, etc.) works well enough, preventing 10-50% of dental decay. (The most well known patent in this area is on stannous fluoride as used in CrestÒ toothpaste, by Mueller. Mueller was also the first dentist to publicly threaten laws against prenatal vitamins with fluoride in the early 60s.) Fluoride is also a nutrient that is prescribed by doctors as teeth are growing.

If fluoride is started in pregnancy, when the first baby teeth start to grow, prevention will be pretty close to 100% according to about 5 good studies. However, there is a reason why it is highly unlikely a pregnant woman would get prenatal fluoride unless she went out of her way to ask for it. In the United States it is legal to sell fluoride for anyone except pregnant women, the very people who need it the most. You can sell fluoride for babies, adults, teenagers, lactating moms, grandmothers, women in general, but you can not say a word about pregnancy on the label of any product that contains any fluoride. It is specifically illegal to put fluoride in products like prenatal vitamins, thanks to the dental lobby, way back in 1966. To this day they refuse to allow it.

(If you would like to see them in operation, see Leverett DH. Clinical trial of the effect of prenatal fluoride supplements in preventing dental caries. NIH-NIDR-NO1-DE-32441; April 1992. Available free of charge from: Mr. Wayne Little / Public Information and Reports Section / Room 2C35 Building 31 / National Institute of Dental Research / 9000 Rockville Pike / Bethesda, MD 20892 / (301) 496-4261. (Or see summary in Caries Research 1997; 31:174-179.) In this huge clinical trial, it was found that something like 90% of children were cavity-free if they started fluoride at either of two times, pregnancy or birth. However, the conclusion was not that either starting time is fine. A few years later the same author is pushing waiting until age 3 years to begin supplements. Assessment of dental fluorosis in relation to the dosage of dietary fluoride supplements used. NIH-NIDR-NO1-DE-22593; August 1994. Prenatal fluoride remains illegal.)

If fluoride is started a little later, at birth, when the first permanent teeth start to grow, prevention is still very good, averaging about 75% in a half-dozen trials. Starting fluoride at birth became very popular with pediatricians when fluoride was added to prescription infant vitamins in about 1962. (These products were invented independently by at least 3 pediatricians Drs. Peebles, Margolis, and Hamberg.) Infant fluoride in vitamins is almost ubiquitous in some countries, particularly in areas with low fluoride in the water supply. There are lots of young people today who have no fillings at all, thanks to their pediatricians. The doses first used were a little too high, and some of these people also have a slightly frosted appearance in their front teeth.

Another way to get fluoride is fluoridated water, which both puts fluoride on the surface of grown teeth and builds fluoride into growing ones. In some parts of the world the use of fluoridated water is very common (e.g., about half of the USA is fluoridated), and this amount of fluoride prevents about half of dental decay where it is used.

Most modern children born since about 1960 got fluoride from either their water or their pediatrician, and, as a rule, have pretty nice teeth compared to their parents. Nothing other than the fluoride difference has been found to explain the good teeth. Both groups have been found to have the same germs, eat the same amount of sugar, etc.

(A good general book about fluoride and teeth is Fluorides and Dental Caries  by E. Newbrun. A good journal article about taking fluoride supplements from birth is Archives of Oral Biology  1978; 23:111 by R. Aasenden. Starting fluoride at birth has been standard pediatric practice for the last 36 years, but this is now being discontinued at the urging of the American Dental Association. Many kids now start at age 6 months. There are only two clinical trials of this start time / dose, and the results are pretty poor both in cavity prevention and in how many kids get mild fluorosis.)

However, there are two slight disadvantages to using fluoride to prevent cavities. The first one is that if a child gets too much, it will cause teeth to get white spots (called fluorosis). This mainly happens with too much fluoride right at birth when the child is very small and the dose (at least in the old days) is relatively large. The way that fluoride causes the spots is to slow down the motion of the proteins in the teeth. (Generally, slowing things down is what fluoride does in most biological systems, and this is an important general concept.) The disadvantage of white spots on teeth can be corrected by just using the right dose during infancy and childhood. 

The second disadvantage is sort of a fluke. If parents see that their kids teeth are going to last forever because of not getting cavities, they tend to spend more money on braces. Braces cost about $2,000, which is more than the cavities would have cost, so this is not a trivial issue. This trend was seen in all the trials that looked for it, especially a prenatal fluoride study by Glenn that we'll cover in a minute. These fluoride kids do not have more crooked teeth than other kids, it is just that braces make more sense on teeth that are not rotting out as fast as they are growing in. When we get to the connection to birth defects, well start with a tooth defect, but these braces are a big part of the story.

The second most popular (but relatively rare) use of fluoride is in the prevention of a bone disease, osteoporosis, although there is not much to go on for evidence. The highest amount of fluoride I have seen suggested is 10 mg F per day, for people 8-25 years old, for the prevention of osteoporosis. (Dustin 1970, Fluoride in Medicine, TL Visher, ed, page 185. This suggestion was rejected on page 192. A more reasonable approach is about 1 mg F per day to prevent osteoporosis. See Osteoporosis, Mayes 1986, page 64.)