Currently, about two-thirds of US households have fluoridated water, and the CDC has made
nationwide fluoridation of drinking water a top priority for the prevention of cavities.
The use of fluoride, however, is something of a hot button issue.
For example, a recent study showed that consumer-generated videos versus industry-generated videos on
YouTube were much more likely to have an anti-fluoride sentiment.
This is not new.
In 1945, Grand Rapids, Michigan became the first US city to implement community fluoridation
of the water supply.
And in the decades that followed, several conspiracy theories developed around the practice,
including speculation of a plot to impose a communist regime in the United States.
Of course, fluoride is not just found in tap water.
It’s also found naturally and fortified in certain foods, can be found in varnish
or gels at the dentist’s office, and is a common ingredient in mouth rinses and toothpastes.
So, how does fluoride prevent cavities, and what does the research say about the benefits
of its use?
Now, in general, there’s bacteria on your teeth, which can form microcolonies, and when
these microcolonies coalesce, it creates a layer of dental plaque.
Bacteria have a hard time getting into the tooth due to the outer layer of enamel which
is composed of a hard substance called hydroxyapatite, a type of calcium phosphate crystal with the
chemical formula Ca10(PO4)6(OH)2.
Now, if the bacteria on the tooth surface start to overgrow, they can metabolize sugary
foods and drinks and generate acid, which can cause the hydroxyapatite to break down.
Without hydroxyapatite, the enamel surface of the tooth can weaken and allow bacteria
to enter, causing permanent damage - this is called a cavity.
If it goes on long enough, the bacteria can infect the root of the tooth, and this can
be really painful.
So this is where fluoride comes in.
Fluoride can replace the OH group in hydroxyapatite to create fluorapatite with the chemical formula
Ca10(PO4)6(F)2.
In general, fluorapatite, is more dense and less soluble than hydroxyapatite, so it’s
less likely to demineralize.
Fluoride also accumulates in your teeth over time, so while fluoride treatments are useful
throughout your life, treatments are generally more important during childhood and adolescence.
Alright, so how well do fluoride treatments work?
One meta-analysis that looked at 20 studies exploring the effect of fluoridation of drinking
water on cavities in children, found that fluoride in the water leads to a 35% reduction
of tooth decay of baby teeth and a 26% reduction in tooth decay of permanent teeth.
Another meta-analysis looked at 22 studies exploring the effect of applying a fluoride
varnish to children’s teeth every 3 to 6 months at the dentist’s office, and found
a 37% reduction in baby teeth and a 43% reduction in tooth decay in permanent teeth.
A third meta-analysis looked at 25 studies focusing on fluoride gel treatments given
at least one time a year at the dentist’s office, generally to children older than 6
years old, which showed a reduction of 28% in tooth decay.
A fourth meta-analysis looked at 35 studies that the effect of fluoridated mouth rinses
given daily to every other week, and found a 27% reduction in tooth decay.
Now, if we look at meta-analyses of studies that focus on fluoridated toothpaste, one
found that it decreases tooth decay and that the effect is stronger with higher fluoride
concentrations in the toothpaste, higher frequency of tooth brushing, and supervised brushing.
This was further supported by another meta-analysis that looked carefully at the amount of fluoride
in the toothpaste.
This study showed that brushing with fluoridated toothpaste with at least 0.1% concentration
of fluoride significantly prevents tooth decay in children and adolescents aged 16 years
or less.
There was a 23% reduction in tooth decay at concentrations of 0.1% to 0.125% fluoride
and up to a 36% reduction in concentrations ranging from 0.24% to 0.28% fluoride.
Now, while fluoride can be toxic at doses well above those used for dental hygiene,
the main concern with using fluoride has generally been fluorosis.
Fluorosis, is not a disease, but rather a cosmetic condition caused by overexposure
to fluoride.
Fluorosis is very common, with up to 41% of children and adolescents having some form
of it.
Usually it takes the form of subtle white patches on the teeth that are barely noticeable.
In moderate to severe cases, w hich occur in less than 4% of the population, there can
be significant mottling of the teeth with brown staining.
While fluorosis is not generally a health concern, it can lead to social stigma.
A meta-analysis of 25 studies looked at whether brushing teeth with fluoridated toothpaste
is linked to fluorosis, and found that brushing the teeth of an infant under 1 year old may
increase the risk of fluorosis, but that relationship was weak.
There was a stronger relationship for children between the ages of 12 months and 6 years
of age.
If these children brushed with a toothpaste that was higher than 0.1% fluoride or more,
they had a 30% chance of developing fluorosis.
This means that the risks of tooth decay, which are decreased over fluoride concentrations
of 0.1% fluoride or more must be balanced with the risk of fluorosis which increases
at fluoride concentrations over 0.1% fluoride.
All right, as a quick recap … Tooth decay and dental cavities are one of the leading
health concerns around the world.
In general, fluoridation of the water supply, and applying fluoride to the teeth via varnishes,
gels, mouth rinses, and toothpaste has helped decrease tooth decay.
While fluoride is generally considered safe at the concentrations used in fluoridated
products, overexposure can lead to fluorosis.
In some cases, risking fluorosis may be preferable to risking tooth decay in children at high-risk
for tooth decay.
Therefore, it may be beneficial to discuss all treatment options with your dentist.
In addition, the American Dental Association recommends preventing overexposure by brushing
children’s teeth with only a grain-of-rice sized smear of fluoridated toothpaste between
when the teeth begin to erupt to 3 years of age, and up to a pea-sized bead of toothpaste
for children over 3 years old.
For children that are old enough to brush their own teeth, it’s also a good idea to
monitor their brushing to decrease the likelihood that they swallow the toothpaste, which can
also lead to overexposure and fluorosis.