Fluoride and prevention of cavities

The data is quite clear on fluoride: it is highly effective at preventing cavities, and the safest and most effective way to apply it is directly onto the enamel of the teeth. Nonetheless, we still hear a lot of misconceptions about fluoride, so we'd like to clear those up first, followed by some very clear and easy recommendations.

History of fluoride: Fluoride is a common element in the earth’s crust. It is naturally found in all water and most plants. The naturally-occurring fluoride content of freshwater ranges between less than 0.05 ppm (“parts per million”) and up to about 14 ppm (Portland’s is less than 0.05 ppm). Fluoride’s effect on teeth was first discovered in the early twentieth century when it was noticed that communities with naturally fluoride-rich water had fewer cavities. So communities with low levels started adding it to their water, and it worked—the number of cavities dropped dramatically.

So what’s the controversy? Well, adding any supplement to a water supply is a complicated topic, which is what has led to a bit of controversy around fluoride more than you would find around other important elements we ingest, like calcium or iron. When something's added to water, it’s harder to control the dose that people end up consuming, because they drink different amounts of water. The best known negative impact of too much fluoride is staining of the teeth, but there are debated links between excessive intake and bad sounding things like bone cancer and a drop in IQ points - but that's only for much higher levels than is typically found. Just because something is potentially harmful in excessive quantities doesn't mean it is harmful at normal levels of exposure. Calcium, iron, etc., are just as dangerous in excess quantities. Fortunately, the amount of fluoride needed to prevent cavities is very low and quite safe. So by using a low dose of fluoride appropriately you can prevent the need for treatment of cavities, which are certainly more harmful to the body than a maintaining a safe balance with fluoride. Cavities and fillings can be painful, traumatic, have their own side effects, and certainly quite expensive for families, so finding a safe balance here is key.

How does fluoride work, anyway? Here's the science. Fluoride has three specific actions:

Inhibits bacterial growth
Halts the breakdown of tooth enamel
Rebuilds enamel stronger than it otherwise would be

When cavity-forming bacteria in our mouths digest our food, they create acid that eats away at tooth enamel, and this is what leads to cavities. But if fluoride is present in the saliva, these harmful bacteria are inhibited. In addition, our enamel will use the fluoride to create a stronger enamel on the surface of our teeth called "fluoroapatite". This high-quality enamel not only is harder to break down because it is more resistant to acid, it also rebuilds itself harder and stronger than ever. And even though I’ve heard countless dentists and pediatricians claim it, currently there is little evidence that fluoride gets into the enamel via the bloodstream, it appears to be most effective when coming into direct contact with the enamel surface, where all the action is.

What’s the best way for children to get their fluoride? While the current protocol recommended by most pediatricians and dentists for kids in Portland is a prescribed daily fluoride supplement, this approach is inherently flawed. Why? As noted above, fluoride needs to come into direct contact with the enamel to be incorporated. The problem is that if you take your entire day’s fluoride dose all at once, it will be washed away by saliva, food and drink, and your teeth will see very little of it while your bloodstream absorbs most of it. You'll see some brief benefit for that moment it passes through your mouth, and possibly minimal exposure via your bloodstream, but the majority will go elsewhere in your body, leading to side effects. In other words, while it works, you will get less benefit and more side effects when you swallow it. Preferably, the teeth should be exposed to frequent, low doses of fluoride. What’s a good source of this that is readily available? Toothpaste!

General recommendations

Before we address the fluoride dosages, let’s first review some important general dental health advice, this stuff is equally as important and applies to all ages:

Avoid grazing. Try to eat only at meals and scheduled snacks. It’s not the total amount of sugar that your child eats in a day that counts, but rather the total amount of time that food spends in their mouth. Frequent eating or nursing will feed cavity-forming bacteria on the surface too frequently and lead to cavities. Let your child eat or nurse a full meal or snack, and then take a good break — the food in their belly will nourish them, while the bacteria in their mouth will starve. A quick mouth rinse with water after meals can help, too. If you're a gardner, think of it like watering deep and thoroughly once a week instead of lightly every day.
Limit milk, juice and soda. If they do drink some from time to time as a treat, offer it with meals instead of between meals. Otherwise, water is the preferred drink.
Limit gummy fruits and candies. Even natural versions, these stick to teeth and help bacteria burrow holes into the enamel.
If you have lots of cavities, limit contact of saliva with your child. Cavity forming bacteria are contagious! Preferably have the parent with fewer cavities do most of the sharing, then see your dentists regularly and have all of your cavities filled and cared for to keep as much of your bacteria at bay as possible.

And, finally, la pièce de résistance:

Fluoride recommendations

For infants and toddlers aged 6 months through 3 years:

Total safe fluoride dose not to exceed 0.25 mg per day = 1 pea-sized amount of fluoride toothpaste total per day
Recommended amount: 1 small smear 2-3 times daily.
Fluoride toothpaste labels may say not to give to kids under a certain age, but if you follow these recommendations carefully it is safe to administer.
It does not need to be a “baby” or "kids" toothpaste. Any fluoride toothpaste will do, but we like natural options like Tom’s of Maine "Clean and Gentle" with fluoride (be careful to see that there is fluoride in the toothpaste, some are fluoride-free).
Start as soon as they have their first tooth.
Apply a tiny *smear* to the tooth/teeth with a brush or cloth 2-3 times daily, AFTER nursing or eating, never before.
The frequency is the most important factor - try not to skip brushing.
It doesn’t need to be a battle. Try to do a good job when possible, but other times at least take 5 seconds to put a smear of fluoride toothpaste on their teeth with rather than skip it completely. If they’ll let you, try to do a bit of brushing, either with a finger brush, washcloth, or toothbrush. It’s OK even if they just want to chew on their toothbrush until the toothpaste is gone, we prefer this to nothing at all.
Remember, it’s the frequency that matters more so than quality at this age, and it should be in the range of 2 to 3 times daily.
See your dentist twice yearly and ask for fluoride varnish applications. These are safe and effective. Our favorite dental clinics are Sprout Pediatric Dentistry and Portland Children’s Dentistry.

For older children:

For ages 3 to 6 years: total safe fluoride dose not to exceed 0.5 mg per day = 2 pea-sized amounts of toothpaste total per day. (Recommended: 1/2 pea-sized amount 2-3 times daily)
For ages 6 years and up: total safe fluoride dose not to exceed 1 mg per day = 4 pea-sized amounts of toothpaste total per day. (Recommended: 1/2 to 1 pea-sized amount 2-3 times daily)
Brush AFTER eating and drinking never before—we want that fluoride to sit in the mouth as long as possible.
After brushing, they can briefly rinse their tongue with water then spit (not swallow), to get the toothpaste taste off their tongue if desired, but don’t have them swish the water around which would wash off all the fluoride from their teeth, and don’t have them swallow the water.
Best times to brush are AFTER breakfast and BEFORE bed.
If you would like additional protection (recommended), have them quickly apply a tiny dab of fluoride toothpaste to their teeth with a finger or brush (or use a fluoride rinse) after lunch in addition to brushing morning and night.
See your dentist twice yearly and ask for fluoride varnish applications. These are safe, effective topical fluoride applications that go directly onto the teeth.

What if your dentist has a problem with the topical approach?

You might share with them this quote by Rebecca Slayton, D.D.S, Ph.D, a member of the AAP Section on Pediatric Dentistry and Oral Health Executive Committee and previous chair of the pediatric dentistry department at OHSU: “When it comes to caries (AKA cavities) prevention, the most effective mechanism is the remineralizing action caused by the exposure of tooth surfaces to frequent, low concentration sources of fluoride such as fluoridated toothpaste, fluoride rinses and gels, fluoride varnish and fluoridated water. Fluoride supplementation should still be considered, but only after determining all sources of fluoride exposure for the child.” (From “Fluoride facts: What pediatricians need to know about fluoride agents for children, including supplementation.” Rebecca L. Slayton. AAP News 2010;31;30.)

Furthermore, the AAP statement, Fluoride Use in Caries Prevention in the Primary Care Setting, (Pediatrics. September 2014, VOLUME 134 / ISSUE 3) says the following: "The mechanisms of fluoride are both topical and systemic, but the topical effect is the most important, especially over the life span." And it backs up this statement with a reference to an article which summarizes the issue as follows (my emphasis): "The level of fluoride incorporated into dental mineral by systemic ingestion is insufficient to play a significant role in caries prevention. The effect of systemically ingested fluoride on caries is minimal. Fluoride 'supplements' can be best used as a topical delivery system by sucking or chewing tablets or lozenges prior to ingestion." (from Featherstone JD. Prevention and reversal of dental caries: role of low level fluoride. Community Dent Oral Epidemiol. 1999;27(1):31–40). There simply is no evidence to support ingested fluoride, and I suspect at some point their recommendations will likely change to reflect this in the future.

When might fluoride supplements be indicated? Only in rare circumstances. If you have a child with special needs, such as autism, and are unable to brush their teeth, for example. Speak with us if so, we can come up with a dental plan for you. If your child simply has a higher risk of cavities, such as based on their enamel or family history, we would generally recommend increasing the frequency of your fluoride brushings rather than the dosing — that will be more effective as well as safer. Also, follow the above general tips more closely, and see your dentist more regularly to have fluoride varnishes applied.

Healthy Schedule

After birth (within 24 hours)
Newborn visit (day 3-5 of age, home visits encouraged)
2 weeks
2 months
4 months
6 months
9 months
12 months
15 months
18 months
24 months
30 months
Yearly thereafter