54 l © 2025 American Dental Association
Section 2: Safety
Despite limitations with the quality and consistency of the fluorosis data from the 2011–2016
NHANES survey and findings of changes in fluorosis over time, it is important to emphasize that
the vast majority of fluorosis is mild or very mild and not readily apparent to the casual observer.
Moreover, the NHANES surveys have consistently found that severe fluorosis is quite rare, affecting
no more than 2% of children and adolescents in any year of the survey, with prevalence generally well
below 1%.246 Whether severe fluorosis has anything more than a cosmetic effect on affected teeth
has been called into question, but a consensus reached during the early 2000s was that severe dental
fluorosis was an adverse health effect. Specifically, members of a committee convened by the NRC for
the EPA concluded that severe dental fluorosis involves damage to the tooth structure, and that the
EPA’s drinking water standard should aim to prevent the occurrence of this unwanted condition.26
As described in Questions 28 and 29, the USPHS recommended in 2015 that the optimal water
fluoride concentration be reduced to 0.7 mg/L throughout the United States.39 This was done to
provide the best balance of protection from tooth decay while reducing the risk of dental fluorosis.
It is important to note that it will take several more years for the change in recommended water
fluoride concentrations to be reflected fully in any studies of dental fluorosis, including NHANES data,
because fluorosis occurs during tooth development and doesn’t become apparent until those teeth
erupt some 6–8 years later. Thus, it is not possible for the 2011–2016 NHANES data to reflect any
changes resulting from the new water fluoride recommendations.
The Effects of Dental Fluorosis
In contrast to severe fluorosis, very mild, mild, and moderate dental fluorosis have no effects on tooth
function but are associated with tooth enamel being more resistant to decay. A study published in
2009 investigated the relationship between dental fluorosis and tooth decay in US schoolchildren.253
The study clearly demonstrated that teeth with dental fluorosis were more resistant to tooth decay
than were teeth without dental fluorosis. Not only should the cavity-preventive benefits of fluoridation
be considered when evaluating policy to introduce or retain water fluoridation, but the cavity-
preventive benefits associated with having mild dental fluorosis should also be considered.
Limited research on the psychological effects of dental fluorosis on children and adults has been
conducted. However, a 2010 literature review that assessed the relationships between perceptions
of dental appearance/oral health-related quality of life (OHRQoL) and dental fluorosis concluded that
very mild to mild dental fluorosis has little impact, and some evidence suggested that mild dental
fluorosis is associated with enhanced quality of life.254 When evaluating the OHRQoL of children by
tooth decay (cavities) and dental fluorosis experience, a 2007 study concluded that cavities and
malocclusion were associated with negative impacts, while mild dental fluorosis had a positive
impact on children’s and parents’ quality of life.255
As discussed later in Question 29, dental fluorosis is a result of the over-ingestion of fluoride from
all sources during tooth development, and not just fluoride from fluoridated water. Other sources
of fluoride that have been linked to the development of dental fluorosis include ingestion of fluoride
toothpaste (using and swallowing too much toothpaste when brushing), use of dietary fluoride
supplements, and fluoride intake from other beverages and foods. Additionally, studies have suggested
that other factors, including living at higher altitudes and with higher average temperatures, can
increase fluorosis prevalence256 and that diagnoses of dental fluorosis sometimes do not seem to
match known fluoride exposures.257
Section 2: Safety
Despite limitations with the quality and consistency of the fluorosis data from the 2011–2016
NHANES survey and findings of changes in fluorosis over time, it is important to emphasize that
the vast majority of fluorosis is mild or very mild and not readily apparent to the casual observer.
Moreover, the NHANES surveys have consistently found that severe fluorosis is quite rare, affecting
no more than 2% of children and adolescents in any year of the survey, with prevalence generally well
below 1%.246 Whether severe fluorosis has anything more than a cosmetic effect on affected teeth
has been called into question, but a consensus reached during the early 2000s was that severe dental
fluorosis was an adverse health effect. Specifically, members of a committee convened by the NRC for
the EPA concluded that severe dental fluorosis involves damage to the tooth structure, and that the
EPA’s drinking water standard should aim to prevent the occurrence of this unwanted condition.26
As described in Questions 28 and 29, the USPHS recommended in 2015 that the optimal water
fluoride concentration be reduced to 0.7 mg/L throughout the United States.39 This was done to
provide the best balance of protection from tooth decay while reducing the risk of dental fluorosis.
It is important to note that it will take several more years for the change in recommended water
fluoride concentrations to be reflected fully in any studies of dental fluorosis, including NHANES data,
because fluorosis occurs during tooth development and doesn’t become apparent until those teeth
erupt some 6–8 years later. Thus, it is not possible for the 2011–2016 NHANES data to reflect any
changes resulting from the new water fluoride recommendations.
The Effects of Dental Fluorosis
In contrast to severe fluorosis, very mild, mild, and moderate dental fluorosis have no effects on tooth
function but are associated with tooth enamel being more resistant to decay. A study published in
2009 investigated the relationship between dental fluorosis and tooth decay in US schoolchildren.253
The study clearly demonstrated that teeth with dental fluorosis were more resistant to tooth decay
than were teeth without dental fluorosis. Not only should the cavity-preventive benefits of fluoridation
be considered when evaluating policy to introduce or retain water fluoridation, but the cavity-
preventive benefits associated with having mild dental fluorosis should also be considered.
Limited research on the psychological effects of dental fluorosis on children and adults has been
conducted. However, a 2010 literature review that assessed the relationships between perceptions
of dental appearance/oral health-related quality of life (OHRQoL) and dental fluorosis concluded that
very mild to mild dental fluorosis has little impact, and some evidence suggested that mild dental
fluorosis is associated with enhanced quality of life.254 When evaluating the OHRQoL of children by
tooth decay (cavities) and dental fluorosis experience, a 2007 study concluded that cavities and
malocclusion were associated with negative impacts, while mild dental fluorosis had a positive
impact on children’s and parents’ quality of life.255
As discussed later in Question 29, dental fluorosis is a result of the over-ingestion of fluoride from
all sources during tooth development, and not just fluoride from fluoridated water. Other sources
of fluoride that have been linked to the development of dental fluorosis include ingestion of fluoride
toothpaste (using and swallowing too much toothpaste when brushing), use of dietary fluoride
supplements, and fluoride intake from other beverages and foods. Additionally, studies have suggested
that other factors, including living at higher altitudes and with higher average temperatures, can
increase fluorosis prevalence256 and that diagnoses of dental fluorosis sometimes do not seem to
match known fluoride exposures.257
