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J Am Dent Assoc, Vol 131, No 1, 93-100.
© 2000 American Dental Association
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TRENDS

JADA Continuing Education

TRENDS IN UNTREATED CARIES IN PRIMARY TEETH

OF CHILDREN 2 TO 10 YEARS OLD



L. JACKSON BROWN, D.D.S., PH.D., THOMAS P. WALL, M.A., M.B.A. and VICKIE LAZAR, M.A., M.S.


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 
Background. This article is the second in a series of three that focus on recent changes in the caries status of children and adolescents in the United States.

Methods. This study is based on analyses of data regarding untreated carious primary teeth among children 2 to 10 years of age from the first and third National Health and Nutrition Examination Surveys, or NHANES I and NHANES III. The NHANES is conducted periodically by the National Center for Health Statistics of the Centers for Disease Control and Prevention.

Results. Overall, the number of carious primary teeth among children 2 to 10 years old decreased from 1.42 as measured in NHANES I to 0.63 as measured in NHANES III. The number of carious primary teeth in children 2 to 10 years old also decreased across four demographic variables: age, sex, race and poverty level.

Conclusions. The number of untreated carious primary teeth among children has declined. Since the 1970s, the absolute difference in untreated caries between disadvantaged children in the United States and the rest of the U.S. child population has narrowed, although not to the same extent as in permanent teeth.

Practice Implications. On average, children of preschool and elementary-school age have less untreated caries than in the past. More often, dentists do not need to treat on a first visit. This provides more opportunity to introduce these children to preventive dentistry at an early age.

Second in a three-part series

This is the second in a series of three articles analyzing the improvement in oral health among children since the early 1970s. It will report changes in untreated caries in the primary teeth of children aged 2 to 10 years. A major focus of the study is how children from low-income households have fared in this regard relative to other segments of the population. A third article will consider the total caries (both treated and untreated) experience among children and adolescents.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 
Data reported and discussed here are based on analyses of data from two of the National Health and Nutrition Examination Surveys, or NHANES I1,2 and NHANES III.3 The NHANES is a periodic survey conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention. A major purpose of this survey is to measure and monitor indicators of the nutrition and health status of the United States’ civilian, noninstitutionalized population. Each survey is based on a complex sample design consisting of a multistage, stratified probability sample of clusters of people in geographic areas. Data for the NHANES are collected from participants through face-to-face interviews, physical and dental examinations, and laboratory tests.

NHANES I was conducted with a nationwide probability sample of approximately 28,000 people, aged 1 to 74 years, from the civilian, non-institutionalized population of the continental United States, excluding people living on American Indian reservations. The survey started in April 1971 and was completed in June 1974.

NHANES III was conducted with a nationwide probability sample of 39,695 people, 2 months of age or older, from the civilian, noninstitutionalized population in the 50 states and the District of Columbia. Several groups of people were over-sampled to ensure statistically reliable estimates: blacks, Mexican-Americans, people 2 months to 5 years of age, and people 60 years of age and older. NHANES III was conducted from October 1988 through October 1994.

Dental caries levels in primary teeth were recorded using the dft/s index. This index, in aggregate, represents the sum of the following components:

– d = decayed teeth or untreated caries;
– f = filled teeth;
– t = primary teeth;
– s = surfaces of those teeth.

For our study, we used tooth-and surface-level data to create dt and ds indexes. We modified tooth and surface codes in NHANES I to make them more compatible with the dental coding scheme used in NHANES III.2 We used the SUDAAN statistical package (Release 7.11, Research Triangle Institute) to calculate standard errors and perform statistical tests because it can adjust for the correlation introduced by the complex sample design.

A subject’s age in both NHANES I and NHANES III is age as reported at the time of the dental examination. In this article, we have divided the data for primary dentition into two groups: those for children 2 to 5 years old and those for children 6 to 10 years old. The first group includes the age range during which most primary teeth are present and most permanent teeth have not erupted. The second group represents the ages when both primary and permanent teeth are present (in other words, mixed dentition).

Among children between the ages of 2 and 10 years, the number of untreated carious primary teeth decreased by 0.79 teeth between 1971 and 1994.

Poverty level in both NHANES I and NHANES III is defined as the ratio of family income to the federal poverty line. Each year, the U.S. Bureau of the Census establishes the federal poverty line and adjusts it by family composition and age of the family reference person. For this article, we created the following poverty categories:

– income at or below the poverty line;
– income ranging from greater than 100 percent to 200 percent of the poverty line;
– income ranging from greater than 200 percent to 300 percent of the poverty line;
– income greater than 300 percent of the poverty line.

The percentage of missing data on the family income variable was noticeably higher in NHANES III than in NHANES I. We compared the caries experience of children for whom data on the family income variable were missing with that of children for whom data on the family income variable were available to identify possible bias associated with missing income data in NHANES III. We detected no significant differences.

We coded race and ethnicity information in NHANES III in a way to make it most consistent with race information in NHANES I and thus maintain consistency over time. Mexican-Americans were grouped with whites, and Hispanic blacks were grouped with blacks. We dropped the residual racial category of "other" owing to a relatively large sampling variation.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 CONCLUSION
 REFERENCES
 
Number of untreated carious teeth. Overall. Among children between the ages of 2 and 10 years, the number of untreated carious primary teeth (the dt component of the dft index) decreased by 0.79 teeth—from 1.42 as measured by NHANES I to 0.63 as measured by NHANES III. Similarly, the number of untreated carious primary surfaces decreased by 1.71 surfaces, or from 2.95 to 1.24 among children 2 to 10 years of age (TableGo). This represents a 55.6 percent decline in untreated carious teeth and a 58 percent decline in untreated carious surfaces among children. (Because data for carious primary surfaces follow the same trends as data for carious primary teeth, from this point forward we will discuss only the number of untreated carious teeth. Data on carious primary surfaces can be found in the table.)


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  		TABLE NUMBER OF UNTREATED CARIOUS PRIMARY TEETH AND SURFACES, AMONG CHILDREN 2 TO 10 YEARS OLD, NHANES* I (1971–1974) AND NHANES III (1988–1994).{dagger}

 
By age. The number of untreated carious primary teeth among children between the ages of 2 and 5 years decreased from 0.96 as measured by NHANES I to 0.67 as measured by NHANES III (a decrease of 30.2 percent). Among 6- to 10-year-olds, the number of carious primary teeth decreased by 1.15 teeth, or from 1.75 to 0.60, during the same period (a decrease of 65.7 percent) (TableGo).

By poverty level. As can be seen in the table, between NHANES I and NHANES III, the average number of untreated carious primary teeth decreased among children at or below the poverty level and among children above the poverty level. In both NHANES’ measurement periods, children at or below the poverty level experienced a higher level of untreated caries in primary teeth than did children above the poverty level. The absolute level of decrease (0.80 teeth) in the average number of carious primary teeth among children at or below the poverty level was about equal to the level of decrease (0.85 teeth) among children above the poverty level.

Black children experienced a higher level of untreated decay in primary teeth than did white children.

Children at or below the poverty level had an average of 1.96 carious primary teeth as measured by NHANES I. This average decreased to 1.16 primary teeth as measured by NHANES III, representing a 40.8 percent decline. Similarly, the number of carious primary teeth among children who were above the poverty level decreased from 1.28 in NHANES I to 0.43 in NHANES III, a 66.4 percent decrease. As depicted in Figure 1Go, the average number of carious primary teeth decreased across all four poverty levels between NHANES I and NHANES III. In NHANES I, the average number of carious primary teeth across all four poverty categories ranged from a low of 0.69 teeth (among those above 300 percent of the poverty level) to a high of 1.96 teeth (among those at or below the poverty level). In NHANES III, these low and high averages decreased to 0.19 and 1.16 teeth, respectively.



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  		Figure 1. Average number of untreated carious primary teeth among children 2 to 10 years of age by poverty level (First National Health and Nutrition Examination Survey, 1971–1974,1,2 and Third National Health and Nutrition Examination Survey, 1988–19943).

 
By race. In both NHANES’ measurement periods, black children experienced a higher level of untreated decay in primary teeth than did white children. Among white children, the number of carious primary teeth decreased by 0.85 teeth, or from 1.38 as measured in NHANES I to 0.53 as measured in NHANES III (a decrease of 61.6 percent). Similarly, among black children, the number of carious primary teeth decreased by 0.84 teeth, or from 1.60 to 0.76, during the same period (a decrease of 52.5 percent) (TableGo).

By sex. Among boys 2 to 10 years of age, the number of carious primary teeth decreased by 60.0 percent, or from 1.55 teeth in NHANES I to 0.62 teeth in NHANES III. Among girls, the number of carious primary teeth decreased 50.0 percent, or from 1.28 teeth to 0.64 teeth, during the same period (TableGo).

By age and poverty level. In NHANES I, the average number of carious primary teeth among children 2 to 5 years old who were at or below the poverty level was 1.25 teeth. In NHANES III, the average number of carious primary teeth among 2- to 5-year-olds at or below the poverty level was 1.12 teeth. The change was not statistically significant. Children above the poverty level had an average of 0.88 carious primary teeth in NHANES I. They experienced a statistically significant decrease of 0.41 teeth down to an average of 0.47 untreated carious teeth in NHANES III (TableGo).

The average number of carious primary teeth among children 6 to 10 years old who were at or below the poverty level was 2.47 teeth in NHANES I and 1.19 in NHANES III, a decrease of 1.28 teeth or 51.8 percent. Those above the poverty level had an average of 1.58 carious primary teeth in NHANES I and 0.39 carious primary teeth in NHANES III. This is a decrease of 1.19 teeth for a 75.3 percent decline (TableGo).

By race and poverty level. In both NHANES’ measurement periods, among white and black children at or below the poverty level, black children exhibited a lower level of untreated caries in primary teeth than white children did. In NHANES I, white children at or below the poverty level had an average of 2.09 carious primary teeth, and black children at or below the poverty level had an average of 1.75 primary teeth. In NHANES III, the average number of carious primary teeth among white children at or below the poverty level decreased 43.5 percent to 1.18 teeth. Among black children at or below the poverty level, the decrease was 49.7 percent, to 0.88 carious primary teeth (TableGo).

For those above the poverty level, in both NHANES’ measurement periods, white children exhibited a lower level of untreated caries in primary teeth than black children did. In NHANES I, black children above the poverty level had an average of 1.42 carious primary teeth. In NHANES III, the average decreased 54.9 percent, to 0.64 carious primary teeth. White children above the poverty level had an average of 1.26 carious primary teeth in NHANES I. This decreased to 0.36 carious primary teeth in NHANES III, a decline of 71.4 percent (TableGo).

Children without untreated caries. Children 2 to 5 years old. As illustrated in Figure 2Go, among children 2 to 5 years old who were at or below the poverty level, the percentage who had no untreated carious primary teeth increased from 68.0 percent in NHANES I to 70.6 percent in NHANES III (Figure 2Go). Among children of the same ages who were above the poverty level, the percentage without untreated caries increased from 77.0 percent in NHANES I to 85.1 percent in NHANES III. By the time of NHANES III, regardless of poverty level, more than 70 percent of children 2 to 5 years of age did not have any untreated carious primary teeth, although most of the primary dentition was present and therefore at risk for caries.



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  		Figure 2. Percentage of children 2 to 10 years of age without untreated carious primary teeth (First National Health and Nutrition Examination Survey 1971–1974,1,2 and Third National Health and Nutrition Examination Survey, 1988–19943).

 
Children 6 to 10 years old. Changes in the percentage of children 6 to 10 years old without untreated caries were more substantial. Among children 6 to 10 years old who were at or below the poverty level, the percentage who had no untreated carious primary teeth increased from 35.0 percent in NHANES I to 57.2 percent in NHANES III. Among children 6 to 10 years old who were above the poverty level, the percentage who had no untreated carious primary teeth increased from 51.0 percent in NHANES I to 80.8 percent in NHANES III (Figure 2Go).

Extent of untreated caries among children with untreated caries. The average number of untreated carious primary teeth among children with untreated caries declined between NHANES I and NHANES III. The most apparent improvement was the reduction in percentage of untreated caries among children with large numbers of carious teeth. Figures 3Go and 4Go show that among 2- to 5-year-olds and 6- to 10-year-olds, regardless of poverty status, there has been a shift from several carious primary teeth in NHANES I to one carious primary tooth in NHANES III.



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  		Figure 3. Percentage of children 2 to 5 years of age by number of carious teeth among those with untreated carious primary teeth (First National Health and Nutrition Examination Survey, 1971–1974,1,2 and Third National Health and Nutrition Examination Survey, 1988–19943).

 


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  		Figure 4. Percentage of children 6 to 10 years of age by number of carious teeth among those with untreated carious primary teeth (First National Health and Nutrition Examination Survey, 1971–1974,1,2 and Third National Health and Nutrition Examination Survey, 1988–19943).

 
Children 2 to 5 years old. Figure 3Go shows data for children 2 to 5 years old who had untreated caries. The percentage of these children at or below the poverty level who had one carious primary tooth increased from 20.3 percent in NHANES I to 25.2 percent in NHANES III. In contrast, the percentage of children 2 to 5 years old at or below the poverty level who had four or more carious primary teeth decreased from 46.2 percent in NHANES I to 37.5 percent in NHANES III.

Figure 3Go also shows that the percentage of children 2 to 5 years old above the poverty level who had one untreated carious primary tooth increased from 28.0 percent in NHANES I to 36.4 percent in NHANES III. In contrast, the percentage of children 2 to 5 years old above the poverty level who had four or more untreated carious primary teeth decreased from 37.5 percent in NHANES I to 31.5 percent in NHANES III.

Children 6 to 10 years old. Figure 4Go shows data for 6- to 10-year-old children with untreated caries. The percentage of these children at or below the poverty level who had one carious primary tooth increased from 19.3 percent in NHANES I to 38.2 percent in NHANES III. In contrast, the percentage of children 6 to 10 years old at or below the poverty level who had five or more untreated carious primary teeth decreased from 31.4 percent in NHANES I to 15.8 percent in NHANES III.

Figure 4Go also shows that the percentage of children 6 to 10 years old above the poverty level who had one untreated carious primary tooth increased from 32.7 percent in NHANES I to 55.2 percent in NHANES III. In contrast, the percentage of children 6 to 10 years old above the poverty level who had five or more untreated carious primary teeth decreased from 24.2 percent in NHANES I to 7.7 percent in NHANES III.


   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
CONCLUSION
 REFERENCES
 
The findings presented in our previous article4 documented a marked decline in untreated caries in permanent teeth among 6- to 18-year-old children in the United States. As we have reported here, children aged 2 to 10 years also have shown improvement in the amount of untreated caries in the primary dentition. Overall, the number of untreated carious primary teeth among children 2 to 10 years old dropped by 55.6 percent between NHANES I and NHANES III. This improvement occurred in both the group aged 2 to 5 years (primary dentition period) and the group aged 6 to 10 years (mixed dentition period). Untreated caries in primary teeth has diminished both in prevalence and extent across time for broad segments of the population (black and white, male and female). This reduction, however, is not as large as it was with permanent teeth.

All 6- to 10-year-old children, regardless of poverty level, experienced significant declines in the level of untreated decay in primary teeth between NHANES I and NHANES III. This also was true for children 2 to 5 years of age above the poverty level. However, we did not find the reduction in untreated decay in children aged 2 to 5 years who were at or below the poverty level to be statistically significant. Moreover, among these children, the percentage who had no untreated caries remained essentially the same (68.0 percent in NHANES I and 70.6 percent in NHANES III). These findings for pre-school children living at or below the poverty level are the one disturbing chapter in an otherwise positive story.

The implications of these data for public policy are important. Something different is taking place among preschool children living at or below the poverty level. First, prevention of caries may be less effective in the primary dentition. Second, a larger portion of caries that does occur goes untreated in these children than in children living above the poverty level. It is well-known that these children do not use dental services as frequently as the rest of the children in their age group.5–7 Medicaid originally was intended to provide these children with access to dental services, but that has not really happened. If the nation wants to see commensurate improvement in the amount of untreated dental disease in preschool children living in poverty, then programs and funds must be established to provide these children with care. Perhaps policy analysis and formulation should concentrate on making Medicaid work for preschool children or, if it does not, on replacing it with a program that does.

The implications of these trends in caries and untreated caries are important for dental practice as well. Today, fewer children visit the dentist in need of treatment for caries. As a consequence, dentists can focus even more on primary prevention. In contrast to the generations of children in the 1950s and 1960s, today’s children can be introduced even in their early years to a lifetime of preventive dentistry. These case mix changes are being documented in treatment data.8,9 Plainly, the practice of dentistry—especially dentistry for children—is making a transition that will result in a larger role for diagnosis and prevention. Many of these improvements in caries extend into the adulthood, all the way to middle age. Consequently, dental care of adult populations is becoming more prevention-oriented as well.


   CONCLUSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
REFERENCES
 
In summary, the data we have presented in this article and the first one in the series4 show that untreated caries in both primary and permanent teeth of U.S. children has diminished, in both prevalence and extent, for broad segments of the child population. The upcoming third article in this series will consider the total experience of caries (both treated and untreated) in permanent teeth and surfaces among children and adolescents.


   FOOTNOTES
 

Mr. Wall is manager, Statistical Research, American Dental Association, Health Policy Resources Center, Chicago.


Ms. Lazar is manager, Health Policy Analysis, American Dental Association, Health Policy Resources Center, Chicago.


Dr. Brown is associate executive director, American Dental Association, Health Policy Resources Center, 211 E. Chicago Ave., Chicago, Ill. 60611. Address reprint requests to Dr. Brown.


   REFERENCES
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES
 

  1. National Technical Information Service, Division of Health Examination Statistics. National health and nutrition examination survey (NHANES I) 1971–1974. Hyattsville, Md.: U.S. Department of Commerce; 1979. Dental data tape catalog 4235.

  2. Thearmontree A, Eklund SA. Comparison between NHANES I and NHANES III: comparable NHANES I tooth and surface data (abstract 2076). J Dent Res 1999;78(special issue):365.

  3. National Center for Health Statistics. Third National Health and Nutrition Examination Survey, 1988–1994, NHANES III Examination Data File (CD-ROM). Hyattsville, Md.: U.S. Department of Health and Human Services; Centers for Disease Control and Prevention; 1996. Public use data file documentation 76,200.

  4. Brown LJ, Wall TP, Lazar V. Trends in untreated caries in permanent teeth of children 6 to 18 years old. JADA 1999;130:1637–44.[Abstract/Free Full Text]

  5. Bloom B, Gift HC, Jack SS. Dental services and oral health: United States, 1989. Hyattsville, Md.: U.S. Public Health Service, Centers for Disease Control and Prevention, National Center for Health Statistics; 1992. U.S. Department of Health and Human Services publication PHS 93–1511.

  6. Manski RJ, Moeller JF, Maas WR. Dental services: use, expenditures, and sources of payment, 1987. JADA 1999;130:500–8.[Abstract/Free Full Text]

  7. Tang JM, Altman DS, Robertson DC, O’Sullivan DM, Douglass JM, Tinanoff N. Dental caries prevalence and treatment levels in Arizona preschool children. Public Health Rep 1997;112(4):319–29.[Medline]

  8. Eklund SA, Pittman JL, Smith RC. Trends in dental care among insured Americans: 1980 to 1995. JADA 1997;128:171–8.[Abstract/Free Full Text]

  9. Eklund SA, Pittman JL, Smith RC. Trends in per-patient gross income to dental practices from insured patients, 1980–1995. JADA 1998;129:1559–65.[Abstract/Free Full Text]




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