10 l © 2025 American Dental Association
Section 1: Effectiveness and Benefits
Fluoride has a third mechanism of action that involves disruption of the ability of bacteria to
metabolize carbohydrates and produce acids.35 It can also hinder the ability of the bacteria to stick
to the tooth surface.75
Fluoride and other minerals, including calcium and phosphate, are present in saliva59,75 and are stored
in dental plaque. To hinder the formation of tooth decay or rebuild tooth surfaces, fluoride must be
constantly present in low concentrations in saliva and plaque.59 Frequent exposure to small amounts
of fluoride, such as that which occurs when drinking fluoridated water, helps maintain the reservoir of
available fluoride in saliva and plaque to resist demineralization and enhance remineralization.59,76 In other
words, drinking fluoridated water provides the right amount of fluoride at the right place at the right
time. Fluoride in water and water-based beverages is consumed many times during the day, providing
frequent contact with tooth structures and making fluoride available to fluoride reservoirs in the mouth.
This explains why fluoride at the low levels found in fluoridated water helps prevent tooth decay.59
Additionally, fluoride ingested during tooth formation becomes incorporated into the tooth structure,
making the teeth more resistant to acid attacks and demineralization.77–81 In particular, this pre-
eruptive exposure to fluoride, before the teeth come into the mouth during childhood, can play a
significant role in preventing tooth decay in the pits and fissures of the chewing surfaces, particularly
of molars.59,82,83 Sources of fluorides in the United States that provide this pre-eruptive effect include
fluoridated water, dietary fluoride supplements, and fluoride present in foods and beverages.
Pre-eruptive effects are sometimes called systemic, while post-eruptive effects are called topical.
However, these terms really refer to different things. Pre- and post-eruptive refer to the timing
of fluoride benefits, while systemic and topical refer to the mode of administration or source of
fluoride. Defining the preventive effects of fluoride from a specific source as solely systemic or
topical is not entirely accurate. For example, water fluoridation prevents tooth decay due to both
a systemic effect during tooth development and a topical effect at the time of ingestion as well
as from being present in saliva.
Today, it is understood that the maximum reduction in tooth decay occurs when systemic and topical
effects are combined, that is, when fluoride has been incorporated into the tooth during formation
and when it is available at the tooth surface during demineralization and remineralization. Water
fluoridation works in both ways to prevent tooth decay.75,78,80,82,83
The maximum reduction in tooth decay occurs when fluoride has been incorporated
into the tooth during formation and when it is available at the tooth surface during
demineralization and remineralization. Water fluoridation works in both ways to
prevent tooth decay.
Section 1: Effectiveness and Benefits
Fluoride has a third mechanism of action that involves disruption of the ability of bacteria to
metabolize carbohydrates and produce acids.35 It can also hinder the ability of the bacteria to stick
to the tooth surface.75
Fluoride and other minerals, including calcium and phosphate, are present in saliva59,75 and are stored
in dental plaque. To hinder the formation of tooth decay or rebuild tooth surfaces, fluoride must be
constantly present in low concentrations in saliva and plaque.59 Frequent exposure to small amounts
of fluoride, such as that which occurs when drinking fluoridated water, helps maintain the reservoir of
available fluoride in saliva and plaque to resist demineralization and enhance remineralization.59,76 In other
words, drinking fluoridated water provides the right amount of fluoride at the right place at the right
time. Fluoride in water and water-based beverages is consumed many times during the day, providing
frequent contact with tooth structures and making fluoride available to fluoride reservoirs in the mouth.
This explains why fluoride at the low levels found in fluoridated water helps prevent tooth decay.59
Additionally, fluoride ingested during tooth formation becomes incorporated into the tooth structure,
making the teeth more resistant to acid attacks and demineralization.77–81 In particular, this pre-
eruptive exposure to fluoride, before the teeth come into the mouth during childhood, can play a
significant role in preventing tooth decay in the pits and fissures of the chewing surfaces, particularly
of molars.59,82,83 Sources of fluorides in the United States that provide this pre-eruptive effect include
fluoridated water, dietary fluoride supplements, and fluoride present in foods and beverages.
Pre-eruptive effects are sometimes called systemic, while post-eruptive effects are called topical.
However, these terms really refer to different things. Pre- and post-eruptive refer to the timing
of fluoride benefits, while systemic and topical refer to the mode of administration or source of
fluoride. Defining the preventive effects of fluoride from a specific source as solely systemic or
topical is not entirely accurate. For example, water fluoridation prevents tooth decay due to both
a systemic effect during tooth development and a topical effect at the time of ingestion as well
as from being present in saliva.
Today, it is understood that the maximum reduction in tooth decay occurs when systemic and topical
effects are combined, that is, when fluoride has been incorporated into the tooth during formation
and when it is available at the tooth surface during demineralization and remineralization. Water
fluoridation works in both ways to prevent tooth decay.75,78,80,82,83
The maximum reduction in tooth decay occurs when fluoride has been incorporated
into the tooth during formation and when it is available at the tooth surface during
demineralization and remineralization. Water fluoridation works in both ways to
prevent tooth decay.
