“Every tooth in a man’s head is
more valuable than a diamond”. Healthy teeth are essential to general
health. Dental decay or caries, affects the majority of populations in
industrialized and many developing countries. It is characterised by the
dissolution of the dental enamel and dentine. This eventually destroys the
affected tooth surface or the tooth itself. The immediate cause is organic
acid

produced by micro-organisms present on the tooth. Dental plaque consists
of bacteria and a matrix of extracellular polysaccharides produced from
sucrose by the bacteria. Tooth plaque, specific bacteria, diet, fluoride and
saliva are all involved in the dental caries process. In recent decades,
preventive measures have helped to dramatically lower levels of dental caries
in industrialized populations. The most important of these measures is
exposure to an appropriate level of fluoride, from various sources, including
water, food and toothpaste.

Dental caries is a multifactorial
disease, related to:

The presence of microorganisms
that cause caries, such as Streptococcus mutans, and Streptococcus
sobrinus
Fermentable carbohydrates (e.g.
sugars) in the diet, particularly when consumed frequently
Susceptible teeth, such as in
the early stages of development, after injury or in malnutrition or
chronic disease
Time: caries increase over time
as teeth erupt and surfaces become at risk.

Good oral health
requires a clean water supply, sufficient for brushing and cleaning teeth
regularly from an early age. Poor oral hygiene may also result in periodical
problems since the dental plaque may induce gingival inflammation and deep
pockets.

While fluoride
intake from drinking water and a balanced, low sugar diet are probably the
most important factors in reducing dental caries, a lack of clean water for
basic oral hygiene may tip the balance towards earlier and more severe
patterns of caries. Where fluoride concentrations in water or in the diet are
known to be low, community water fluoridation is safe and cost-effective.
While there are established benefits from adding fluoride to waters with low
natural fluoride, fluorosis remains a problem in areas of where the natural
concentration of fluoride is high.

Effects of Water
Fluoridation on Teeth: Dental Fluorosis vs. Tooth Decay

From
a risk/benefit perspective, water fluoridation is an unacceptably risky
practice — a fact that is evident even if teeth are the only tissue in the body
that one considers.

Modern
research shows that fluoride ingestion (from water alone, or all sources
combined) is far more likely to cause teeth to develop fluorosis than
it is to prevent a cavity. As
demonstrated below, both fluoridated water and total daily fluoride intake
have weak relationships with tooth decay which are very difficult to
detect in modern populations. By contrast, the relationship between fluoride
ingestion and dental fluorosis remains clear, obvious, and easy to detect. In
short, fluoridated water causes more damage to teeth than benefit. Accordingly,
even if all other potential adverse effects are ignored (e.g., arthritis,
bone fracture,
brain damage,
osteosarcoma,
thyroid disease), the
practice of fluoridating water fails a risk-benefit analysis on the subject of
tooth quality alone.

Early Understandings

Fluoride’s
ability to cause fluorosis was well known at the time U.S. health authorities
endorsed water fluoridation in the 1950s. At that time, however, U.S.
they believed that fluoridating water at 1 part per million (ppm) would
have very little effect on fluorosis rates, but a very large effect on tooth
decay.

In
a seminal paper published in 1950, Dr. Harold Hodge produced a figure that
illustrated the predicted effect that fluoridation would have on both tooth
decay and dental fluorosis. Hodge’s figure, which is reproduced below,
estimated that as the fluoride level in water was increased from 0 to 1 ppm,
the tooth decay rate would plummet by over 60%, while the fluorosis rate would
only marginally increase. Based on this calculation, Hodge concluded that
fluoridation could reduce tooth decay without a trade-off of increased
fluorosis. He thus recommended that dentists and doctors show the figure to
patients who were concerned about fluoridation to assure them of the program’s
safety and efficacy.

Current Understandings

Hodge’s
predictions have not aged well. Research spanning from the 1980s to the present
has demonstrated that the risk-benefit equation vis-a-vis dental fluorosis and
tooth decay is far different than what Hodge and U.S. health authorities had
estimated. Indeed, current data shows the opposite of what was predicted:
namely, raising the fluoride level in water from 0 to 1 ppm has little
measurable effect on tooth decay, but has a large and significant effect on
dental fluorosis.

Consider,
for example, the following studies:

1. Iowa Fluoride Study (1990s
– 2000s)

Following
publication of the NIDR’s findings, dentists dismissed the significance of the
results by claiming that the reduced effectiveness of fluoridation was simply
because of the increased use of fluorides in dentistry as well as the
“multiplier effect” where children in non-fluoridated areas are exposed to
fluoridated drinking water through processed beverages, etc. This idea,
however, has been seriously challenged by the results of an NIH-funded,
multi-million dollar, decades-long study carried out by researchers at the
University of Iowa.

Known
as the “Iowa Fluoride Study,”
the aim of the study was to monitor the fluoride intake of a group of children
from birth to adolescence in order to determine to what extent total fluoride
ingestion from all sources is associated with tooth decay and dental fluorosis.
Under the “multiplier effect” theory, the more fluoride the children were
exposed to, the lower their rate of tooth decay should be. However, in 2009,
the Iowa researchers reported that total daily intake of fluoride from birth
through adolescence had no significant relationship to whether the children
developed any cavities in their teeth. By contrast, total fluoride intake was
significantly related to whether the children developed dental fluorosis.

Health Watch: How Bottled Water Affects Your Teeth

Millions of Americans are embracing a
healthy lifestyle and turning to bottled water as part of their diet. Bottled
water is often marketed as being better for you, but it may be doing your teeth
a disservice. Your bottled water could be missing some elements that promote
oral health.

For over 60 years, the United States
has been involved in a public health program called community water
fluoridation. Many communities throughout the nation added fluoride
to their water supply, and the result was a significant decrease in
childhood cavities.
In fact, community water fluoridation is the single most effective public
health measure for tooth decay
prevention to date.