NCHS Data Brief ■ No. 53 ■ November 2010

u.s. department of health and human services

Centers for Disease Control and Prevention

National Center for Health Statistics

Key findings

Data from the National 

Health and Nutrition 

Examination Survey, 

1999–2004 and the 1986–

1987 National Survey of 

Oral Health in U.S. School 

Children

•	 Less than one-quarter of 

persons aged 6–49 in the 

United States had some form 

of dental fluorosis.

•	 The prevalence of dental 

fluorosis was higher in

adolescents than in adults and 

highest among those aged 

12–15.

•	 Adolescents aged 12–15 

in 1999–2004 had a higher 

prevalence of dental fluorosis

than adolescents aged 12–15 

in 1986–1987.

Prevalence and Severity of Dental Fluorosis in the 

United States, 1999–2004

Eugenio D. Beltrán-Aguilar, D.M.D., M.S., Dr.P.H.; Laurie Barker, M.S.P.H.; 

and Bruce A. Dye, D.D.S., M.P.H.

Dental fluorosis refers to changes in the appearance of tooth enamel that are

caused by long- 

(1). Studies conducted in the 1930s showed that the severity of tooth decay

was lower and dental fluorosis was higher in areas with more fluoride in

the drinking water (2). In response to these findings, community water

fluoridation programs were developed to add fluoride to drinking water to

reach an optimal level for preventing tooth decay, while limiting the chance

of developing dental fluorosis (3). By the 1980s, studies in selected U.S.

communities reported an increase in dental fluorosis (4,5), paralleling the

expansion of water fluoridation and the increased availability of other sources

of ingested fluoride, such as fluoride toothpaste (if swallowed) and fluoride

supplements (6). This report describes the prevalence of dental fluorosis

in the United States and changes in the prevalence and severity of dental 

fluorosis among adolescents between 1986–1987 and 1999–2004.

Keywords: children • dental public health • National Health and Nutrition 

Examination Survey • National Survey of Oral Health in U.S. School 

Children

Less than one-quarter of persons aged 6–49 had dental 

fluorosis.

NOTES: Dental fluorosis is defined as having very mild, mild, moderate, or severe forms and is based on Dean’s Fluorosis Index. 

Percentages do not sum to 100 due to rounding.

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2004.

Figure 1. Percent distribution of dental fluorosis among persons aged 6–49: United States, 

1999–2004 

Unaffected

Questionable

Very mild

Mild

Moderate

Severe

60.6

16.5

16.0

4.8

2.0 Less than 1
NCHS Data Brief ■ No. 53 ■ November 2010

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Among persons aged 6–49, 

had moderate fluorosis, and less than 1% had severe fluorosis (Figure 1).

For the remaining three-quarters of persons in this age group, 60.6% were unaffected by dental

fluorosis and 16.5% were classified as having questionable dental fluorosis.

Prevalence of dental fluorosis was higher among younger persons and 

ranged from 41% among adolescents aged 12–15 to 9% among adults aged 

40–49.

Adolescents aged 12–15 had the highest prevalence of dental fluorosis (40.6%) (Figure 2). The

prevalence is lower among older age groups. The lowest prevalence was among those aged 40–49

(8.7%). The prevalence of dental fluorosis among children aged 6–11 (33.4%) was lower than the

prevalence among those aged 12–15 (40.6%).

NOTES: Dental fluorosis is defined as having very mild, mild, moderate, or severe forms and is based on Dean’s Fluorosis Index. Error bars represent 95% 

confidence intervals.

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2004.

Figure 2. Prevalence of dental fluorosis among persons aged 6–49, by age group: United States, 1999–2004 Percent

Age in years

8.7

14.3

28.4

36.1

40.6

33.4

0

10

20

30

40

50

6–11 12–15 16–19 20–29 30–39 40–49
NCHS Data Brief ■ No. 53 ■ November 2010

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Children aged 12–15 in 1999–2004 had higher prevalence of dental fluorosis 

compared with the same aged children in 1986–1987. 

In 1986–1987, 22.6% of adolescents aged 12–15 had dental fluorosis, whereas in 1999–2004,

40.7% of adolescents aged 12–15 had dental fluorosis (Figure 3). The estimates for severe alone

were statistically unreliable.

The prevalence of very mild fluorosis increased from 17.2% to 28.5% and mild fluorosis

increased from 4.1% to 8.6%. The prevalence of moderate and severe fluorosis increased from

1.3% to 3.6%.

NOTES: Dental fluorosis is defined as having very mild, mild, moderate, or severe forms and is based on Dean’s Fluorosis Index. Percentages do not sum to 100 

due to rounding. Error bars represent 95% confidence intervals.

SOURCES: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2004 and National Institute of Dental Research, National Survey of Oral Health 

in U.S. School Children, 1986–1987. 

Figure 3. Change in dental fluorosis prevalence among children aged 12–15 participating in two national surveys:

United States, 1986–1987 and 1999–2004 Percent

60

50

40

30

20

10

0

Dental flourosis

47.1

39.6

30.2

19.7 17.2

28.5

4.1

8.6

3.6

1.3

Unaffected Questionable Very mild Mild Moderate 

and severe

NIDR, 1986–1987 NHANES, 1999–2004
NCHS Data Brief ■ No. 53 ■ November 2010

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Summary

Twenty-three percent of persons aged 6–49 had dental fluorosis in 1999–2004. Approximately

2% had moderate dental fluorosis and less than 1% had severe dental fluorosis. Dental fluorosis

was most prevalent among children aged 12–15, and less prevalent among older age groups. The

prevalence of dental fluorosis among children aged 6–11 was lower than the prevalence among

adolescents aged 12–15. This may be explained by an incomplete set of permanent teeth among

children aged 6–11; some posterior permanent teeth, including premolars and second molars,

erupt between ages 10 and 12.

The levels of very mild, mild, and moderate or severe dental fluorosis were higher among

adolescents aged 12–15 in 1999–2004 than in 1986–1987.

In the analyses of changes in prevalence between both national surveys, moderate and severe

dental fluorosis were aggregated into one category because all estimates of severe fluorosis were

statistically unreliable after stratification (standard error of the percentage was greater than 30%

the value of the percentage).
NCHS Data Brief ■ No. 53 ■ November 2010

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Definitions

Dental fluorosis: Defined as a change in the mineralization of the dental hard tissues (enamel,

dentin, and cementum) caused by long-term ingestion (eating and drinking) of fluoride during

the period of tooth development prior to eruption into the mouth (first 8 years of life for most

permanent teeth excluding third molars). Once the tooth erupts, dental fluorosis refers to a range

of visually detectable changes in enamel. Changes range from barely visible lacy white markings

in milder cases to converged opaque areas and pitting of the teeth in severe forms. After eruption

the pitted areas can become stained yellow to dark brown.

Dean’s Fluorosis Index: Developed in the 1930s by H.T. Dean to assess the prevalence and

severity of dental fluorosis in various communities in the United States (2). Major criteria for

each category are listed below:

•	 Unaffected: The enamel is translucent. The surface of the tooth is smooth, glossy, and

usually has a pale creamy white color.

•	 Questionable: The enamel shows slight changes ranging from a few white flecks to

occasional white spots. This classification is utilized in those instances in which a definitive

determination of the mildest form of fluorosis is not warranted and a classification of

unaffected is not justified.

•	 Very mild: Small opaque paper-white areas are scattered over the tooth surface, but do not

involve as much as 25% of the surface.

•	 Mild: White opaque areas on the surface are more extensive, but do not involve as much as

50% of the surface.

•	 Moderate: White opaque areas affect more than 50% of the enamel surface.

•	 Severe: All enamel surfaces are affected. The major aspect of this classification is the

presence of discrete or confluent pitting.

Prevalence of dental fluorosis: Defined as the proportion of the population with very mild or

higher levels of dental fluorosis, by convention established by H.T. Dean (2). The questionable

category is excluded. 
NCHS Data Brief ■ No. 53 ■ November 2010

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Data source and methods

Data from the National Health and Nutrition Examination Survey (NHANES) were used for

most of these analyses. NHANES is a cross-sectional survey designed to monitor the health

and nutritional status of the civilian noninstitutionalized U.S. population. The oral health exam

was conducted in mobile examination centers by trained dentists. In 1999, NHANES became a

continuous survey with each year of data collection based on a representative sample covering

all ages. The NHANES sample is selected through a complex, multistage design that includes

selection of primary sampling units (PSUs) (counties or county equivalents), household segments

within the PSUs, and finally, sample persons from selected households. The sample design

includes oversampling in order to obtain reliable estimates of health and nutritional measures for 

population subgroups. In 1999–2004, oversampling included non-Hispanic black and MexicanAmerican persons as well as adolescents. Additional information on NHANES can be located at

http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm. 

Data from the 1986–1987 National Survey of Oral Health in U.S. School Children were also

used, which was conducted by the National Institute of Dental Research (NIDR, currently the

National Institute of Dental and Craniofacial Research). The oral health exam was conducted

using portable dental equipment on the school premises by trained dentists. The 1986–1987

NIDR sample was selected through a multistage design that included selection of school districts,

schools, and classrooms. Because the 1986–1987 NIDR survey was school-based, children not

attending school were not part of the sampling frame. Additional information for the 1986–1987

NIDR survey is available in the public-use data file documentation and survey methodology

report (7).

Both surveys included intraoral assessment of all permanent teeth conducted by trained and

standardized dental examiners who used the Dean’s Fluorosis Index (2). Accordingly, each tooth

was assigned one of six diagnostic codes: unaffected, questionable, very mild, mild, moderate,

and severe. Examiners in both surveys reached acceptable levels of interexaminer reliability

against a standard examiner (8–10). Data from the 1986–1987 NIDR survey represent the first

national data on dental fluorosis, while data from the 1999–2004 NHANES represent the most

recent national data. The age group 12–15 was used to compare changes between surveys

because, on average, all permanent teeth are fully erupted at that age.

Publicly available datasets from both surveys were used to calculate a person-based score for

dental fluorosis following Dean’s criteria, that is, using the score corresponding to the two most

affected teeth. For example, in order to have a category of “moderate” fluorosis, the person

should have at least two permanent teeth with the score of moderate. For analyses using age, data

from the 1999–2004 NHANES were grouped into six age groups (6–11, 12–15, 16–19, 20–29,

30–39, and 40–49) and comparisons to the 1986–1987 NIDR survey used data from respondents

aged 12–15.

Population estimates and standard errors were calculated in SAS-callable SUDAAN software

(release 9.0; Research Triangle Institute, Research Triangle Park, N.C.). 

by the National Center for Health Statistics and NIDR to account for differing probabilities of

selection, nonresponse, and noncoverage, were used for analysis. The standard errors of the

percentages were estimated using Taylor Series Linearization to take into account the complex

sampling design. Graphs include 95% confidence intervals.
NCHS Data Brief ■ No. 53 ■ November 2010

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About the authors

Eugenio D. Beltrán-Aguilar and Laurie Barker are with the Centers for Disease Control and

Prevention’s (CDC) National Center for Chronic Disease Prevention and Health Promotion,

Division of Oral Health. Bruce A. Dye is with CDC’s National Center for Health Statistics,

Division of Health and Nutrition Examination Surveys.

References

1.	 Aoba T, Fejerskov O. Dental fluorosis: Chemistry and biology. Crit Rev Oral Biol Med

13(2):155–70. 2002.

2.	 Dean HT. The investigation of physiological effects by the epidemiological method. Report

no 19. Washington, DC: American Association for the Advancement of Science. 1942.

3.	 CDC. Fluoridation of drinking water to prevent dental caries. MMWR 48:933–40. 1998.

4.	 Leverett D. Prevalence of dental fluorosis in fluoridated and nonfluoridated communities—A

preliminary investigation. J Public Health Dent 46(4):184–7. 1986.

5.	 Szpunar SM, Burt BA. Dental caries, fluorosis, and fluoride exposure in Michigan

schoolchildren. J Dent Res 67(5):802–6. 1988.

6.	 Mascarenhas AK. Risk factors for dental fluorosis: A review of the recent literature. Pediatr

Dent 22(4):269–77. 2000.

7.	 National Institute of Dental Research. Oral health of United States children. The National

Survey of Oral Health in U.S. School Children, 1986–1987. Public-use data file documentation

and survey methodology. Bethesda, MD: National Institutes of Health. 1992.

8.	 National Institute of Dental Research. Oral health of United States children. The National

Survey of Dental Caries in U.S. School Children, 1986–1987. National and regional findings.

NIH Publ no 89–2247. Bethesda, MD: National Institutes of Health. 1989.

9.	 Dye BA, Barker LK, Selwitz RH, Lewis BG, Wu T, Fryar CD, et al. Overview and quality

assurance for the National Health and Nutrition Examination Survey (NHANES) oral health

component, 1999–2002. Community Dent Oral Epidemiol 35(2):140–51. 2007.

10.	Dye BA, Nowjack-Raymer R, Barker LK, Nunn JH, Steele JG, Tan S, et al. Overview and

quality assurance for the oral health component of the National Health and Nutrition Examination

Survey (NHANES), 2003–04. J Public Health Dent 68(4):218–26. 2008.
NCHS Data Brief ■ No. 53 ■ November 2010

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Suggested citation

Beltrán-Aguilar ED, Barker L, Dye BA.

Prevalence and severity of dental fluorosis 

in the United States, 1999–2004. NCHS

data brief, no 53. Hyattsville, MD: National

Center for Health Statistics. 2010.

Copyright information

All material appearing in this report is in 

the public domain and may be reproduced 

or copied without permission; citation as to

source, however, is appreciated.

National Center for Health 

Statistics

Edward J. Sondik, Ph.D., Director

Jennifer H. Madans, Ph.D., Associate 

 Director for Science

Division of Health and Nutrition 

Examination Surveys

Clifford L. Johnson, M.S.P.H., Director

U.S. Department of

Health & Human Services

Centers for Disease Control and Prevention

National Center for Health Statistics

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