52 l © 2025 American Dental Association
Section 2: Safety
27. What is dental fluorosis or enamel fluorosis?
Answer
Dental fluorosis, also called enamel fluorosis, is a change in the appearance of the tooth enamel that
only occurs when younger children consume too much fluoride, from all sources combined, over
extended periods when teeth are developing under the gums. It can cause opaque or white blemishes
on teeth. The permanent teeth (except the “wisdom teeth” or third molars) finish their development
when children are 8 to 10 years old, so dental fluorosis only occurs when too much fluoride is
consumed during the period of birth to 8 to 10 years of age (with the first 4 years of life being
most important for the front teeth that are visible when smiling). After that age, there is no
longer any risk of developing fluorosis.236
Fact
Dental fluorosis is associated with total fluoride intake during the ages when teeth are forming, so fluoride
intake not only from water but also from other beverages, foods, and fluoride products, such as toothpaste,
mouthrinses, and dietary fluoride supplements, is important. The best available evidence indicates that the
majority of fluorosis in the United States is caused by the inappropriate ingestion of fluoride products.237
It should be noted that there are many other developmental changes that affect the appearance of tooth
enamel that are not related to fluoride intake, including enamel hypoplasia, demarcated opacities, and
others. In other words, not all opaque or white blemishes on teeth are caused by fluoride. Furthermore,
dental fluorosis occurs among some people in all communities, even in communities that do not have
community water fluoridation or have low natural concentrations of fluoride in their drinking water.238–240
In the United State, the vast majority of dental fluorosis cases are mild or very mild. These mild or very
mild changes to the enamel are only seen when the teeth are dry and clean, such as when a dentist
examines them. For this reason, it is often difficult to detect dental fluorosis in its milder forms, and
even trained specialists can sometimes disagree over the presence of fluorosis or its severity. Mild
or very mild fluorosis has no effect on tooth function and is associated with the teeth being more
resistant to decay. More information on mild dental fluorosis can be found on the ADA’s website.241
Measurement and Classification of Dental Fluorosis
Dental fluorosis usually is assessed by direct visual inspection of the teeth, with or without drying of
the teeth with compressed air or gauze squares. There are several different classification schemes that
vary in the codes used and the degree to which the teeth are dried. Because of how drying the teeth
can affect the detection and assessment of dental fluorosis, some researchers have proposed using
standardized photographs for evaluating dental fluorosis.242,243
In the United States, the most widely used classification is the Dean’s Fluorosis Index, which was
developed by Dr. Trendley Dean in 1942 as part of his pioneering research on water fluoride
concentrations, dental caries, and dental fluorosis.94 For Dean’s Fluorosis Index, each tooth in an
individual’s mouth is rated according to the fluorosis index in Table 3. The individual’s person-level
dental fluorosis score is based on the two most affected teeth in the mouth recorded as the second
most affected tooth. Dean’s Fluorosis Index remains popular for prevalence studies, in large part due
to its simplicity and the ability to make comparisons with findings from a number of earlier studies.244
Section 2: Safety
27. What is dental fluorosis or enamel fluorosis?
Answer
Dental fluorosis, also called enamel fluorosis, is a change in the appearance of the tooth enamel that
only occurs when younger children consume too much fluoride, from all sources combined, over
extended periods when teeth are developing under the gums. It can cause opaque or white blemishes
on teeth. The permanent teeth (except the “wisdom teeth” or third molars) finish their development
when children are 8 to 10 years old, so dental fluorosis only occurs when too much fluoride is
consumed during the period of birth to 8 to 10 years of age (with the first 4 years of life being
most important for the front teeth that are visible when smiling). After that age, there is no
longer any risk of developing fluorosis.236
Fact
Dental fluorosis is associated with total fluoride intake during the ages when teeth are forming, so fluoride
intake not only from water but also from other beverages, foods, and fluoride products, such as toothpaste,
mouthrinses, and dietary fluoride supplements, is important. The best available evidence indicates that the
majority of fluorosis in the United States is caused by the inappropriate ingestion of fluoride products.237
It should be noted that there are many other developmental changes that affect the appearance of tooth
enamel that are not related to fluoride intake, including enamel hypoplasia, demarcated opacities, and
others. In other words, not all opaque or white blemishes on teeth are caused by fluoride. Furthermore,
dental fluorosis occurs among some people in all communities, even in communities that do not have
community water fluoridation or have low natural concentrations of fluoride in their drinking water.238–240
In the United State, the vast majority of dental fluorosis cases are mild or very mild. These mild or very
mild changes to the enamel are only seen when the teeth are dry and clean, such as when a dentist
examines them. For this reason, it is often difficult to detect dental fluorosis in its milder forms, and
even trained specialists can sometimes disagree over the presence of fluorosis or its severity. Mild
or very mild fluorosis has no effect on tooth function and is associated with the teeth being more
resistant to decay. More information on mild dental fluorosis can be found on the ADA’s website.241
Measurement and Classification of Dental Fluorosis
Dental fluorosis usually is assessed by direct visual inspection of the teeth, with or without drying of
the teeth with compressed air or gauze squares. There are several different classification schemes that
vary in the codes used and the degree to which the teeth are dried. Because of how drying the teeth
can affect the detection and assessment of dental fluorosis, some researchers have proposed using
standardized photographs for evaluating dental fluorosis.242,243
In the United States, the most widely used classification is the Dean’s Fluorosis Index, which was
developed by Dr. Trendley Dean in 1942 as part of his pioneering research on water fluoride
concentrations, dental caries, and dental fluorosis.94 For Dean’s Fluorosis Index, each tooth in an
individual’s mouth is rated according to the fluorosis index in Table 3. The individual’s person-level
dental fluorosis score is based on the two most affected teeth in the mouth recorded as the second
most affected tooth. Dean’s Fluorosis Index remains popular for prevalence studies, in large part due
to its simplicity and the ability to make comparisons with findings from a number of earlier studies.244
