Changes in Dental Caries Prevalence in Upstate New York Schoolchildren

7 58 Journal of Public Health Dentistry

Changes in Dental Caries Prevalence in Upstate New York Schoolchildren

Jayanth Kumar, DDS, MPH Elmer Green, DDS, MPH William Wallace, MS Robert Bustard, DDS Bureau of Dental Health New York State Department of Health Room 71 0, Tower Building Albany, NY 12237

Abstract A survey of second and fifth grade children was con-

ducted in upstate New York to determine recent trends in dental caries prevalence. Clinical examinations were conducted on 960 second grade and 837 fifth grade children in 51 schools. A single examiner derived the findings on a uniform basis using a standard protocol. An examination of changes in the percent of caries-free children and mean DMFS/dfs indices revealed that caries prevalence has continued to decline. Although the low SES group in this survey had consistently higher caries levels and a higher treatment need compared to the high SES group, the magnitude of the difference was much smaller compared to the previous survey. Because the sampling was restricted to young children in upstate New York, the trends observed should not be applied to a similar New York City population, to older children throughout New York State, or to children in other states.

Key Words: dental caries, socioeconomic status, treatment needs, disease trends.

Numerous studies have indicated that the prevalence of dental caries in the United States has declined substantially in the last decade (I). Even though this phenomenon was recently identified, Burt (2) has indicated that it could have started at least in the 1960s. While agreement on past experiences of the disease is generally uniform, the prediction of future trends and of the nature of the disease appears to be uncertain.

Graves and Stamm (3) have predicted that this declining trend in caries prevalence will continue in the future. They cite the impact of such factors as healthier life- styles, improved oral health practices, and increased use of preventive agents. Burt (2) has also predicted that the overall caries experience will continue to diminish. Ac-

Send correspondence and reprint requests to Dr. Kumar. Manuscript received: 5/14/90; returned to authors for revision: 7/18/90; accepted for pubhcation: 8/31 /90.

1 Public Health Dent 1991;51(3):158-63

cording to him, the major determinants that might be changing over the years are cariogenic bacteria, sugar consumption, and fluoride exposure. However, Tanzer (4) has suggested that caries may assume an oscillatory behavior, which has been observed with many other infections. Stamm (5) has depicted a plausible scenario of reemergence of caries if reduced caries occurrence leads to inadequate emphasis on disease prevention.

While earlier studies reported the caries decline that occurred in the 197Os, more recent studies indicate that caries is still on the decline. Rozier et al. (6) have reported that the caries decline in North Carolina schoolchildren has been greater since 1976 than it was between 1960 and 1976, with reductions of approximately 50 to 60 percent occurring in whites during the last decade. The National Dental Caries Prevalence Survey results indicate that 49.9 percent of 5-17-year-old children had no decay in their permanent teeth in 1986-87, in contrast to 36.6 percent in a similar 1979-80 survey. During the same period, the average number of decayed, missing, and filled surfaces per child declined from 4.77 to 3.07 (7). The overall trends in dental caries in US schoolchildren during the past 15-16 yearsindicate an average annual decrease in DMFS of approximately 4 percent. In contrast to these studies, standardized epidemiologic surveys conducted by Heifetz et al. (8) in 1980 and 1985 did not show evidence of a significant change in caries prevalence in seven Illinois communities. Also, a recent survey conducted in Kentucky children found the dental caries levels to be substantially higher compared to the national data, indi- cating regional variations in caries prevalence (9).

In New York State data gathered from several indepen- dent studies provide consistent findings to suggest that dental caries prevalence has declined substantially in the last four decades (Table 1). An observation of particular interest is that while the caries decline started immedi- ately after fluoridation began in Newburgh, caries was on the rise in nonfluoridated Kingston at least into the 1960s and then declined (12).

The purpose of this survey was to determine if there

Vol. 51, No. 3, Summer 1991 159

has been a change in caries prevalence in upstate New York schoolchildren in recent years. Caries prevalence data for selected grades are available for upstate schoolchildren. A 1979-80 survey of second and fifth grade populations in upstate New York provides a base- line for the measurement of trends (13).

Methods The sample design was an extension of the concept of

stratified sampling of schools. The stratification was based on geographical regions and socioeconomic level of census tracts or Minor Civil Divisions in which the school was located. The geographic regions represented seven health services areas (HSA) in upstate New York that divide the state into health planning and development regions. The three levels of socioeconomic status (SES) scores of the census tracts were based on a method developed by the Centers for Disease Control and then adapted to upstate New York (14). The calculation of SES scores and the operational definition for classification are shown in Table 2.

"Numerous studies have indicated that the prevalence of dental caries in the United States has declined substantially in the last decade."

The selection of schools was limited primarily to the schools selected in the 1979-80 survey. However, several modifications were made in sample selection. In the pres- ent study, eighth and eleventh grades were excluded because of budgetary constraints. Unlike the previous survey, both second and fifth grade children in each of the schools were included. For seven selected schools not having both second and fifth grade enrollment, a second school in the same school district having enrollment in the other grade was selected. The minimum sample size per grade in each school was set at an average classroom size of 25. Finally, because nutrition-related information was also being collected in this study, the sample size was almost doubled.

TABLE 1 Changes in Dental Caries Prevalence in New York State

Age (Yrs)

New York City 12 Geneva 12-14 Brockport 12 Newburgh 7-1 4 Kingston 7-1 4

Study % Change Reference Period (DMFT) No.

1971-83 45.6 10 1%5-77 41.0 11 1952-75 60.0 11 1944-86 66.7 12 1944-86 58.3 12

Clinical examinations were conducted on 960 second grade and 837 fifth grade children from 51 schools. They represented a population of 133,190 and 163,733 second and fifth grade children, respectively. The average return rate of parental consent forms, whether positive or neg- ative, was 80 percent. However, the overall positive response rate was 51 percent.

The criteria used for diagnosis of dental caries in both the surveys were similar to the World Health Organiza- tion (WHO) guidelines (15). A single examiner derived findings on a uniform basis by utilizing a standard protocol. Examinations were conducted at each location using a mirror and explorer with standard illumination. Radiographs were not taken.

This report deals with the comparison of estimates of decayed, missing, and filled surfaces of teeth (DMFS/dfs) between the surveys conducted in 1979-80 and 1987-88. Also reported are estimated proportions of children with caries-free permanent teeth and filled com- ponents of the DMFS index. The estimates of prevalence data were derived separately for each grade and socioeconomic level, using the methods appropriate for stratified sampling (16). The estimates presented here reflect the sampling weights attached to each strata. The sampling weights were obtained from the distribution of children by socioeconomic status and geographic region in the 1980 census. As a part of the Nutrition Surveillance Program, nutrition-related information and data on an- thropometric measurements were also gathered. The results of that part of the study will be published separately.

Results The characteristics of the sample and the study popu-

lation presented in Table 3 show similarities with respect to certain known variables. A comparison of the proportion of children with a caries-free permanent dentition is shown in Table 4. The results indicate consistently that a larger proportion of second and fifth grade children were free from caries of the permanent dentition in 1987-88

TABLE 2 Method of Calculating Socioeconomic Scores for Upstate

New York Based on the 1980 Census

Median Family % with 4+ Yrs % Unskilled Value Income (MFl) of College (PC) (PU)

0 ~$15,500 ~ 7 . 0 35.0+ 1 15,500-1 7,499 7.0-9.9 26.5-34.9 2 17,500-19,499 10.0-13.9 21.5-26.4 3 19,500-23,999 14.0-21.4 16.5-21.4 4 24,000+ 21.5+ ~ 1 6 . 5

Soaoeconomc score=WFI value) + (PC value) + (PU value) Scores: %7=low; 8-l0=medium; 11-12=hgh.

160 Journal of Public Health Dentistry

than in 1979-80. A comparison of decayed, filled, and missing tooth

surfaces indicates that the caries decline expressed as

TABLE 3 Population Characteristics and the Sample Studied

Upstate New York (%)

Samplet (%)

Male White Free lunch Unemployment rate On food stamps Children living w/

both parents Children living w/

single mother

51.2 88.0, 23.0'

5.6* 10.1* 79.0,

13.0,

50.1 88.3 21.1

5.0 8.6

81.0

16.3

*Data are abstracted from the New York State publication " W d and Adolescent Health Profile," New York State, 1986. Figures refer to children 0-17 years of age (29). tData for the samplewereobtained from thenutrition survey question- naire.

changes in mean DMFS ranged from 57 to 79 percent in permanent teeth (Table 5). In the primary dentition, the change in mean decayed and filled surfaces (dfs) ranged from 8 to 39 percent (Table 6). As in the previous survey, children in the low SES group have slightly higher canes prevalence compared to that of medium and high SES groups. In fifth grade children, the difference in mean DMFSbetween high and low SES groups was 0.7 (0.4,1.0, 95% CI). In the deciduous dentition of second grade children, the difference in mean dfs between high and low SES groups was 0.9 (0.5,1.2,95% CI). In the previous survey, the differences in canes prevalences between high and low SES groups amounted to 1.4 DMFS (0.6,2.2, 95% CI) and 2.8 dfs (2.3,3.3,95% CI) in fifth and second grade children, respectively. However, the absolute re- duction in canes was greater in low SES children both in second and fifth grade.

An examination of the filled component of the DMFS index reveals that children in this survey had fewer fillings compared to children examined a decade ago. How- ever, the proportion of filled surfaces, a reflection of service utilization, has not changed substantially over the years (Table 7). While the untreated caries lesions (D/DMFS) amounted to 16 to 23 percent in the high SES

TABLE 4 Children with Caries-free Permanent Dentition (in Percent) by Year of Examination, Grade, and SES

Percent Caries-free (SE) Diff. 95%

SES n 1979-80 n 1987-88 (in %) CI

Grade 2 (mean age=7.9 years) Low 158 50.5 (3.1) 348 80.6 (2.5) 30.1 22.3,37.9

84.3 (2.4) 21.8 11.9,31.6 Medium 143 62.5 (4.4) 379 High 159 77.5 (3.1) 233 87.9 (2.7) 10.4 2.3,18.4

Low 138 24.3 (3.1) 264 51.5 (3.0) 27.2 18.7,35.6 Medium 160 39.5 (4.4) 320 56.5 (3.6) 17.0 5.8, 28.1 High 1% 31.5 (3.1) 253 64.4 (5.0) 32.9 21.3,44.4

Grade 5 (mean age=10.9 years)

TABLE 5 Dental Canes Prevalence (Mean DMFS) by Grade, Socioeconomic Level, and Year of Examination

Mean DMFS (SE)

SES

Grade 2 Low Medium High

Grade 5 LOW

Medium High

- 1979-80

1.80 (0.06) 1.16 (0.03) 0.58 (0.02)

4.58 (0.24) 2.85 (0.08) 3.16 (0.33)

1987-88 DMFS Difference

0.42 (0.07) 1.38 0.24 (0.06) 0.92 0.24 (0.08) 0.34

1.62 (0.02) 2.96 1.23 (0.13) 1.62 0.92 (0.16) 2.24

95% CI % Change

1.2,1.6 0.8,l.O 0.2,0.5

2.4,3.4 1.3,1.9 1.5,2.9

77 79 59

65 57 71

Vol. 51, No. 3, Summer 1991 161

TABLE 6 Dental Canes Prevalence (Mean dfs) in Primary Teeth by Grade, Socioeconomic Level, and Year of Examination

Mean dfs (SE)

SES



1979-80

5.35 (0.05) 3.86 (0.07) 2.58 (0.25)

2.71 (0.15) 2.43 (0.08) 2.92 (0.10)

1987-88

3.26 (0.07) 2.59 (0.13) 2.38 (0.17)

1.98 (0.06) 2.20 (0.06) 2.26 (0.16)

dfs Difference

2.09 1.27 0.20

0.73 0.23 0.66

95% CI

1.9,2.2 1 .O, 1.5

-0.4,0.8

0.4,1 .O 0.0,0.4 0.3, 1 .O

% Change

39 33 8

27 8

23

TABLE 7 Filled Surfaces and Percent Filled by Year of

Examination, Grade, and SES

TABLE a Distribution of Proximal DMFS by Year of

Examination, Grade, and SES

SES



Filled Surfaces (SE) % Filled (F/DMFS)

1979-80* 1987-88 1979-80 1987-88

0.79 0.20(0.05) 44 48 0.82 0.11 (0.02) 71 46 0.45 0.20 (0.08) 78 84

2.66 l.Og(0.14) 58 67 2.1 2 0.99 (0.1 1) 74 80 2.81 0.71 (0.12) 89 77

SES



1979-80 Mean % Proximal of DMFS* DMFS

0.17 9.4 0.11 9.4 0.08 13.7

0.69 15.0 0.33 11.5 0.41 12.9

1987-88 Mean % Proximal of

DMFS (SE) DMFS

0.04 (0.01) 9.5 0.01 (0.01) 4.1 0.02 (0.05) 8.3

0.09 (0.02) 5.5 0.09 (0.01) 7.3 0.05 (0.02) 5.4

Standard errors were not available. +Standard errors were not available.

group, it was 33 to 52 percent in the low SES group. Although the service utilization (F/DMFS) in the medium SES group was not consistent, the data on the caries prevalence and percent caries-free children followed a pattern similar to the high SES group. An examination of the extent of proximal caries lesions (mesial-distal DMFS), which constitute only 4.1 to 9.5 percent of all lesions, reveals a further decline (Table 8).

Discussion As this survey was undertaken to gather information

needed to describe and define patterns and trends in dental caries prevalence, the selection of schools was largely limited to those schools sampled in the previous survey. However, budgetary constraints and several lo- gistic problems dictated the selection of the final sample. Refusal to participate, school closure, a lower-than-ex- petted response rate, and changes in socioeconomic characteristics complicate the measurement of the precise magnitude of changes. While this selection may have resulted in a "convenient sample," the data presented in

Table 3 illustrate that the sample selected was fairly representative of upstate New York schoolchildren. As similar data for the 1979-80 sample were not available, representativeness of the sample could not be established for the previous survey. The lack of data to establish the comparability of the two samples and the other deficiencies noted in the study suggest that the precision of the estimates presented may be low. Nevertheless, the two surveys are sufficiently similar to permit an examination of trends in caries prevalence.

Although the changes in demographic and socioeconomic characteristics from 1980 to 1988 are to be expected, the race/ethnic composition of children enrolled in upstate New York schools did not change substantially in those years (17). While the median family income in constant dollars showed an improving trend, the poverty rates for children under 18 in upstate New York from 1980 through 1987, as compiled from the Census Bureau's Current Population Survey data tape, show a fluctuation from a high of 16.1 percent in 1983 to a low of 11.1 percent in 1986 (18).

162 Journal of Public Health Dentistry

An examination of changes in the proportion of caries- free children and mean DMFS reveals that caries prevalence has continued to decline. This finding is corrobo- rated by the evidence of declining trends in the average number of restored surfaces, as well as trends in the primary dentition. Although the "dfs" index may not reflect accurately the caries experience in fifth grade children, a comparison of two statistics obtained by using a similar protocol should still be valid for measurement of trends, unless extraction and exfoliation patterns changed dramatically in those years.

Although the methodology for the two surveys was similar, a shift in the application of the diagnostic criteria could have affected the results to some extent. While the assessment of caries is based on subjective criteria, the classification of filled surfaces is mainly based on objec- tive criteria. The fact that the decline is noticeable in the filled surfaces and that the decline is seen in all strata strengthens the findings of a real decline rather than an artifact. This trend is consistent with the findings of the National Dental Caries Prevalence Survey and the North Carolina Survey (6,7).

The relative changes in different SES groups should be viewed in light of possible misclassification of some schools in this survey from the use of 1980 census data. According to Deming (19), such misclassification is to be expected as the natural course of events, as the real universe is always dynamic and the information that is used for classification is, to some extent, always out- dated. The application of this method also suffers from inaccuracies in cases of schools designated as magnet schools. In spite of these deficiencies, this method consistently showed caries levels and treatment needs to be higher in low SES schools in both the surveys.

While the results of this survey are generally encour- aging, approximately 33 to 52 percent of all lesions in low SES groups had not been treated. Further, the low SES group continues to experience higher canes, although the magnitude of the difference among SES levels is smaller when compared to the previous survey. The predominance of pit and fissure caries demonstrates a similar pattern of dental caries in different SES groups.

It is now widely acknowledged that the relation between SES and caries prevalence scores has changed in recent years (3). The National Health Examination Sur- veys of 1963-65 and 1966-70 reported that higher levels of SES were associated with higher caries prevalence (20,21). Since the data on the inverse relationship between SES levels and caries prevalence became evident from the 1979-80 New York State Survey, the New York State Department of Health has developed a policy for targeting school-based programs to high-risk and un- derserved population groups. The socioeconomic score of the census tract/minor civil division has been used in upstate New York for targeting fluoride rinse, dental sealant, and screening programs. Setting such priorities

for school-based programs has created an ongoing de- bate among researchers and public health officials. The National Preventive Dentistry Demonstration Program found that school-based fluoride mouthrinse, daily fluoride tablets, biannual fluoride paste prophylaxis and gel applications, dental health lessons, and biweekly brush- ing and flossing were not consistently effective in a selected population in preventing clinically significant amounts of tooth decay beyond that already prevented by typical home and office care. Because a large amount of decay occurs in a small proportion of the children, the study identified the need for targeting school-based programs to those who are likely to experience the disease (22). Stamm (5) has urged the development of such a policy in both the private and public sectors.

Veatch (23) has criticized the idea of setting priorities based on sex, race, ethnic group, socioeconomic status, the socioeconomic status of a school, or fluoridation status of a community. According to him, the utilitarian strategy of maximizing the good in the community per unit of investment compromises the just claims and rights of some members of the community. However, because of the constraints facing all public health programs, the targeting approach has gained widespread acceptance in publicly supported health care programs (24).

Therefore, in the absence of definitive criteria for targeting individuals at high risk, the strategy of targeting low SES groups for school-based programs appeared to be the best available means for allocating scarce resources. However, the magnitude of the difference in caries prevalence between high and low SES groups in this study was smaller when compared to a previous survey. This narrowing of the gap between high and low SES group has also been reported by Kaufman et al. (25) and Tucker-Englert et al. (26) when other methods for SES classification were employed. A school district on Long Island, NY, with a 34.8 percent enrollment in the free school lunch program, had a higher caries prevalence, more untreated caries, and fewer sealants compared to that of children in a school district with 8.3 percent enrollment in the free lunch program. However, in 8-1 1-year-old children, the difference in mean DMFS between these two groups amounted to less than 0.4 surfaces (25). Although Tucker-Englert et al. (26), found that treatment rates were significantly associated with SES in a survey of adolescents in Texas, the association between DMFS and SES was not statistically significant. This may have been due to the particular method used to determine DMFS scores that resulted in a range restric- tion effect. Nevertheless, to identify those with greatest needs, the operational definition of low SES group may have to be modified in future studies to include only those at the lowest end of the socioeconomic scale.

A finding that could have enormous implications in the future is the reduced need for restorative services in

Vol. 51, No. 3, Summer 1991 163

young children. If the decline in the number of fillings performed by dentists holds true for older children, then the need for visits for check-up, prophylaxis, and topical fluorides at six-month intervals for all children has to be reevaluated. In addition, considering the predominance of pit and fissure caries, the promotion and utilization of sealants assume even greater importance if further re- duction in canes levels is to be accomplished. Another related issue that needs to be examined is the adherence to recently altered guidelines concerning dental radiographs. Because the frequency of caries is low, the need for dental radiographs in young children has been reduced. The current guidelines have been appropriately modified to suit the altered disease patterns (27).

A major limitation of this study is the extent to which these data are generalizable to the New York State population. Because the sampling was restricted to young children in upstate New York, the trends observed should not be applied to a similar New York City population or to older children throughout New York State. Further, such distinct populations as American Indians, children of migrant workers, and recent immigrant populations were not included in this study. More impor- tantly, caries prevalence in different racial groups could not be estimated because of the small number of non- white children surveyed. Studies conducted in such population groups in New York State have indicated a much higher caries prevalence compared to that of white resi- dents (10,28).

To deal with the budgetary constraints and yet over- come the limitations cited above, the New York State Department of Health has developed a standard data collection methodology for implementation in several phases. A study of oral health status of schoolchildren in New York City is being completed. Planning for surveys of distinct population groups such as American Indians and children of migrant workers is in progress. Further, surveys of eighth and eleventh grade children are also being planned. Such a strategy should provide a better picture of dental disease trends in New York State children.

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Changes in Dental Caries Prevalence in Upstate New York Schoolchildren