This article assesses whether or not caries improvements observed in children extend to the adult population and which racial and income groups have benefited. We analyze the following in the permanent tooth surfaces of 18- to 45-year-old adults:

– trends in total caries, according to the decayed, missing and filled, or DMF, index;

– untreated caries—the D component of the DMF index;

– filled caries—the F component of the DMF index.

	METHODS

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
NHANES data. Data reported and discussed here are based on analyses of data from the first and third National Health and Nutrition Examination Surveys, or NHANES I^5,6 and NHANES III.⁷ The NHANES is a periodic survey conducted by the National Center for Health Statistics. Data for the NHANES surveys are collected from participants through face-to-face interviews, physical and dental examinations, and laboratory tests.

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

NHANES III. NHANES III was conducted with a nationwide probability sample of 39,695 people, two months of age or older, from the civilian, noninstitutionalized U.S. population in the 50 states and the District of Columbia. African-Americans, Mexican-Americans, and people 2 months to 5 years of age and 60 years of age and older were oversampled to obtain statistically reliable estimates for these populations. NHANES III was conducted from October 1988 through October 1994.

Caries. Dental caries levels in permanent teeth were recorded using the DMFT/S index. This index, in aggregate, represents the sum of the following components:

– D = decayed teeth or untreated caries;

– M = missing teeth;

– F = filled teeth;

– T = permanent teeth;

– S = surfaces of those teeth.

For this study, we used surface-level data to create DT and DS indexes. We modified surface codes in NHANES I to make them more compatible with the dental coding scheme used in NHANES III.⁵ We used the SUDAAN statistical package (Version 7.11, Research Triangle Institute, Research Triangle Park, N.C.) to calculate standard errors and perform statistical tests because it can adjust for the correlation introduced by the complex sample design.

Age. Age for both NHANES I and NHANES III is age as reported at the time of the dental examination. In this article, the data for permanent dentition is presented overall and for three age groups: 18 to 25 years, 26 to 35 years and 36 to 45 years.

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

– at or below the FPL;

– above the FPL.

Income. Percentage of missing teeth according to the family income variable was noticeably higher in NHANES III than in NHANES I. We compared the caries experience of adults for whom data on the family income variable were missing with that of adults 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.

Race. Race-ethnicity in NHANES III was coded 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. The residual racial category of "other" was dropped owing to relatively large sampling variation.

Education. For this article, we created the following education categories:

– eighth grade or less;

– ninth through 12th grade;

– college.

	RESULTS

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Total number of carious permanent surfaces. Overall. Among adults between the ages of 18 and 45 years, the mean number of carious permanent surfaces, or DMFS, decreased from 38.30 as measured by NHANES I for the 1971–1974 period to 27.86 as measured by NHANES III for the 1988–1994 period. This represents a 27.26 percent decline in mean DMFS among adults (Table 1).

View this table: [in this window] [in a new window]   TABLE 1 MEAN NUMBER OF DECAYED, MISSING OR FILLED SURFACES, OR DMFS, AMONG ADULTS 18 TO 45 YEARS OLD, NHANES I* AND NHANES III.

Although not shown in Table 1, decreases in DMFS were not found in older age groups. DMFS increased from 56.88 in NHANES I to 58.63 in NHANES III among those aged 46 to 55 years. Among those aged 56 to 65 years, mean DMFS increased from 65.78 to 68.97.

By sex. In both NHANES I and NHANES III, mean DMFS was higher among women than among men. For male adults aged 18 to 45 years, mean DMFS decreased by 28.75 percent, or from 36.45 surfaces in NHANES I to 25.97 surfaces in NHANES III. Similarly, for female adults, mean DMFS decreased 25.86 percent, or from 40.02 surfaces to 29.67 surfaces during the same measurement period (Table 1).

The mean DMFS decreased for the three subset adult age groups of 18 to 25 years, 26 to 35 years and 36 to 45 years among both men and women. Consistently, the younger cohort experienced a greater percentage decrease in DMFS than did the older cohort.

By poverty level. In both NHANES’ periods of measurement, the mean DMFS among adults who were above the FPL was higher than that among adults who were at or below the FPL. As can be seen in Table 1, the mean DMFS decreased among both groups between NHANES I and NHANES III. Adults between the ages of 18 and 45 years, at or below the FPL, had a mean DMFS of 34.04 in NHANES I. This mean decreased to 24.72 surfaces in NHANES III, a 27.38 percent decline. Similarly, the mean DMFS among adults who were above the FPL decreased from 38.91 in NHANES I to 28.53 in NHANES III, a 26.68 percent decrease.

The mean DMFS decreased for the three adult subset age groups of 18 to 25 years, 26 to 35 years and 36 to 45 years for those at or below the FPL and for those above the FPL. Consistently, the younger cohort experienced a greater percentage decrease than did the older cohort.

By race. In both NHANES’ periods of measurement, mean DMFS was lower among black adults than among white adults. Among white adults, mean DMFS decreased from 38.92 in NHANES I to 28.12 in NHANES III, a decrease of 27.75 percent. Among black adults, the decrease was from 35.03 surfaces to 27.83 surfaces, a decrease of 20.55 percent (Table 1).

Although not shown in Table 1, mean DMFS decreased for the three adult subset age groups of 18 to 25 years, 26 to 35 years and 36 to 45 years among white adults. Among black adults, the two subset age groups of 18 to 25 years and 26 to 35 years also experienced decreases in mean DMFS. However, a commensurate improvement among older blacks (those aged 36 to 45 years) was not apparent.

By educational level. Adults aged 18 to 45 years who had an educational level of eighth grade or less had a mean DMFS of 41.14 in NHANES I and 26.41 in NHANES III, a decrease of 35.80 percent. Among adults who had an educational level of ninth grade through 12th grade, mean DMFS decreased from 40.12 in NHANES I to 28.50 in NHANES III, a decrease of 28.96 percent. Adults with a college education experienced a decrease of 19.95 percent in mean DMFS, from 34.24 surfaces in NHANES I to 27.41 surfaces in NHANES III (Table 1).

The mean number of decayed, missing or filled surfaces was lower among black adults than among white adults.

Number of carious permanent surfaces. Overall. Among adults between the ages of 18 and 45 years, the mean number of DS decreased from 3.64, as measured by NHANES I for the period 1971–1974, to 1.82 as measured by NHANES III for the period 1988–1994. This represents a 50.00 percent decline in mean DS among adults (Table 2).

View this table: [in this window] [in a new window]   TABLE 2 MEAN NUMBER OF DECAYED SURFACES, OR DS, AMONG ADULTS 18 TO 45 YEARS OLD, NHANES I* AND NHANES III.

Although not shown in Table 2, we also found decreases in DS in older age groups. Among those aged 46 to 55 years, mean DS decreased from 2.65 surfaces in NHANES I to 1.62 surfaces in NHANES III. Mean DS fell from 3.17 to 1.52 among those aged 56 to 65 years.

By sex. As shown in Table 2, mean DS was higher among men than among women in both NHANES I and NHANES III. For male adults aged 18 to 45 years, mean DS decreased by 43.47 percent, or from 3.75 surfaces in NHANES I to 2.12 surfaces in NHANES III. Similarly, for female adults, mean DS decreased 56.94 percent, or from 3.53 surfaces to 1.52 surfaces during the same measurement period. Although not shown in Table 2, mean DS decreased for the three adult subset age groups of 18 to 25 years, 26 to 35 years and 36 to 45 years among both men and women.

By poverty level. In both NHANES’ periods of measurement, mean DS among adults who were at or below the FPL was higher than that among adults who were above the FPL. As can be seen in Table 2 and Figure 1, between NHANES I and NHANES III, mean DS decreased in both groups. Adults between the ages of 18 and 45 years at or below the FPL had a mean DS of 6.50 in NHANES I. This mean decreased to 3.68 in NHANES III, a 43.38 percent decline. Similarly, mean DS among adults who were above the FPL decreased from 3.27 in NHANES I to 1.48 in NHANES III, a 54.74 percent decrease. The differences between the two poverty categories fell from 3.23 surfaces to 2.2 surfaces.

View larger version (29K): [in this window] [in a new window]   Figure 1. Mean number of decayed surfaces among adults aged 18 to 45 years, by federal poverty level, or FPL, status in the First National Health and Nutrition Examination Survey, or NHANES I, conducted 1971–1974,1,2 and the Third National Health and Nutrition Examination Survey, or NHANES III, conducted 1988–1994.3

By race and poverty level. Figure 2 shows that in NHANES I, absolute differences in mean DS between blacks and whites were as large as differences related to poverty status. However, between NHANES I and NHANES III, differences between blacks and whites narrowed from four surfaces to 1.2 surfaces among those below the FPL, and from 3.5 to 1.5 surfaces among those above the FPL. The difference by poverty status narrowed from 2.8 surfaces to 1.9 surfaces among blacks, but remained steady for whites.

View larger version (33K): [in this window] [in a new window]   Figure 2. Mean number of decayed surfaces among adults aged 18 to 45 years, by race, controlling for federal poverty level, or FPL, in the First National Health and Nutrition Examination Survey, or NHANES I, conducted 1971–1974,1,2 and the Third National Health and Nutrition Examination Survey, or NHANES III, conducted 1988–1994.3

Adults without untreated caries in permanent teeth. Among adults aged 18 to 45 years, the percentage without any untreated caries increased 21.7 percentage points, from 49.3 percent in NHANES I to 71.0 percent in NHANES III. Similar increases occurred among the three age groups. For those who were 18 to 25 years old, 45.4 percent were without untreated caries. By NHANES III, 70.7 percent of this cohort was without untreated caries, an increase of 25.3 percentage points (Figure 3). Forty-nine percent of adults between the ages of 26 and 35 years were without untreated caries in NHANES I. This percentage increased to 68.8 percent in NHANES III, an increase of 19.8 percentage points. Among those aged 36 to 45 years, 55.3 percent were without untreated caries in NHANES I and 73.6 percent were without untreated caries in NHANES III, an increase of 18.3 percentage points.

View larger version (31K): [in this window] [in a new window]   Figure 3. Percentage of adults without untreated caries in permanent teeth, by age group, in the First National Health and Nutrition Examination Survey, or NHANES I, conducted 1971–1974,1,2 and the Third National Health and Nutrition Examination Survey, or NHANES III, conducted 1988–1994.3

View larger version (31K): [in this window] [in a new window]   Figure 4. Percentage of adults aged 18 to 45 years without untreated caries in permanent teeth, by federal poverty level, or FPL, status in the First National Health and Nutrition Examination Survey, or NHANES I, conducted 1971–1974,1,2 and the Third National Health and Nutrition Examination Survey, or NHANES III, conducted 1988–1994.3

	DISCUSSION

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

Caries has declined in all adult age groups up to the age of 45 years. Across the entire 18- to 45-years-old age range, total caries experience declined by 27 percent between the early 1970s and the early 1990s. All racial and income subgroups have benefited. Although the results reported here pertain to carious surfaces, similar results were observed when caries was measured on a tooth basis. Thus, caries has become less extensive as measured by the number of teeth and percentage of the dentition affected. Primary prevention through various fluoride modalities, better oral hygiene, oral health promotion and more frequent dental visits have had an impact on caries among adults as well as children.

Birth cohorts have been affected differently. Results in this study indicate that total caries declined among people aged 45 years and younger. However, we did not observe declines in caries experience among adults aged 46 to 65 years. Small increases in mean DMFS from NHANES I to NHANES III among older adults consisted of decreases in the number of DS and MS, and an increase in the number of FS. People aged 46 years in 1994—the last year of the NHANES III survey—were born in 1948. Older people in the group aged 46 to 65 years in NHANES III were born earlier, as were people in the similar age cohort from NHANES I. These people grew up during the early 1950s or before. This was a period before fluoride was widely available, which may be a significant reason the older cohorts did not show caries improvement. Since this study did not include a separate analysis of root caries, which is more prevalent in older adults, additional research in this area is needed.

Large improvements have been registered for untreated caries. Among adults aged 18 to 45 years, untreated caries fell by 50 percent. Again, all subgroups within that age range benefited. The largest absolute decline in untreated caries occurred among blacks. Untreated caries fell from 7.47 surfaces in the early 1970s to 3.33 surfaces in the early 1990s—an improvement of more than 50 percent. While about one-half of the population aged 18 to 45 years demonstrated untreated caries in the early 1970s, by the early 1990s more than 70 percent did not have untreated caries. Improvements in untreated decay do extend to people aged 46 to 65 years. This suggests that a higher percentage of adults are visiting a dentist and receiving treatment, which is consistent with the increasing percentage over time of the population who visited a dentist within the previous year^12–15 and with the marked declines during the previous 20 years in restorative services.^16,17

Results also are encouraging among adults living below the FPL. Total caries experience fell by 27 percent for these people between the two survey periods, while untreated caries declined by more than 40 percent. The percentage of those living below the FPL without untreated caries increased from 34 percent to 53 percent. Nevertheless, those living below the FPL experienced more caries and more untreated caries than did those with higher incomes. This is a problem that must continue to be addressed until the disparities between disadvantaged people and the rest of the population are eliminated.

	CONCLUSION

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
It is apparent that the reduction in caries among children^1–3 has extended to adults. One result is a decline in the need for restorative dentistry. Caries improvements among adults may be associated with birth cohort effects. During the period of NHANES I (1971–1974), young adults 18 to 25 years old grew up before widespread fluoridation. In contrast, those aged 18 to 25 years during the period of NHANES III (1988–1994) grew up when fluoridation and preventive dentistry were more widely available. As more recent data become available, additional trend analysis may be useful in further examining birth cohort effects.

View larger version (121K): [in this window] [in a new window]   Dr. Brown is the associate executive director, Health Policy Resources Center, American Dental Association, 211 E. Chicago Ave., Chicago, Ill. 60611, e-mail "brownja{at}ada.org". Address reprint requests to Dr. Brown.

View larger version (136K): [in this window] [in a new window]   Mr. Wall is the manager, Statistical Research, Health Policy Resources Center, American Dental Association, Chicago.