With these questions in mind, our specific objectives were to describe children with dental insurance and how they compared with children with medical insurance, and to assess the association between dental insurance coverage and having had a PDC visit in the previous year, with particular emphasis on the effect of age and race/ethnicity.

	METHODS

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Data source. We relied on data from the NSCH, which was sponsored and directed by the Maternal and Child Health Bureau of the U.S. Health Resources and Services Administration, along with the Centers for Disease Control and Prevention (CDC) and the National Center for Health Statistics (NCHS).¹³ The survey was conducted between January 2003 and July 2004 and was intended to collect information about the physical, emotional and behavioral health and health care experiences of a large sample of representative U.S. children.⁴

The State and Local Area Integrated Telephone Survey mechanism was used to complete 102,353 telephone surveys of households with children 0–17 years of age, with approximately 2,000 respondents from each of the 50 states and the District of Columbia.¹³ After identifying a household with children, the interviewers asked for the children’s birth dates. The interviewer then randomly selected one child to be the subject of the interview. The respondent was the parent or guardian in the household who was most knowledgeable about the health and health care of the children. In 79 percent of households, this was the child’s mother, and in 17 percent of households, it was the father. Grandparents or other relatives or guardians composed the remainder of the households (4 percent). Surveys were conducted in English or Spanish (6 percent of interviews).¹³

The data file is publicly available and contains population weights, stratum identifiers (that is, state name) and primary sampling unit codes that account for the complex sample design and permit population-based estimates with accurate standard errors. Poststratification adjustments before release of the data ensure that population subgroups were properly represented in the weighted estimates generated from the data set.¹³

Variable selection and sources. Our primary outcome of interest was having dental insurance, which was derived from this NSCH survey question: "Does your child have insurance that helps pay for any routine dental care including cleanings, X-rays and examinations?"¹⁴ There were no other questions about the specific type of dental insurance. The interviewer also asked respondents whether they had health care insurance (henceforth considered synonymous with "medical insurance") and whether this coverage was "Medicaid or SCHIP" ("yes" or "no"), without determining which of the two the child had.¹⁴ We then created mutually exclusive categories for the type of dental insurance. We assigned to the "public dental insurance" category children whose caregiver had responded affirmatively to the dental insurance query and who were reported to have SCHIP/Medicaid health insurance. Children who were reported to have dental insurance and who had medical insurance that was non-Medicaid/SCHIP were considered to have "private dental insurance." We assigned children who were reported to have no dental insurance to the "uninsured for dental care" category.

To characterize the association between dental insurance and a PDC visit during the previous 12 months, we relied on this NSCH survey question: "During the past 12 months, did your child see a dentist for any routine preventive dental care, including check-ups, screenings, and sealants?"¹⁴ This question was not asked of children who were younger than 12 months or who did not yet have any natural teeth.¹³ Before conducting our data analysis, we identified variables hypothesized to be associated with having dental insurance and additional variables potentially associated with PDC utilization, based on a comprehensive literature review. These variables included patient and family variables available in the NCHS, which are listed in Table 1.

– per capita distribution of general dentists¹⁵;

– proportion of dentists participating in Medicaid and SCHIP¹⁶;

– percentage of Medicaid/SCHIP–eligible children who were enrolled.¹⁷

For use in the analysis, we created dichotomous categories for the state per capita dentist distribution (< 54 dentists/100,000 population and 54 dentists/100,000 population; 54 was the median) and the proportion of dentists participating in Medicaid ( 50 percent and < 50 percent).

Race. To enhance our analyses, we created additional variables. We classified Hispanic/Latino ethnicity combined with any race as Hispanic/Latino, and we left the other races unchanged from the original data—white, African-American, multiracial and other (only these four racial groups were provided in the NSCH). Asians were included in the "other race" group.

Metropolitan statistical area. The metropolitan statistical area (MSA) of residence had been suppressed (that is, not released in the public data set) to protect the confidentiality of subjects in certain states where either MSA or non-MSA was relatively unusual. Using methods described by Mayer and colleagues,¹⁸ we recoded MSA from "missing" to "non-MSA" for states with small MSA samples (that is, most subjects lived in non-MSA or more rural locations [Alaska, Idaho, Maine, Montana, North Dakota, South Dakota, Vermont and Wyoming]). Similarly, we recoded MSA status from "missing" to "MSA" for states with small non-MSA samples (that is, Connecticut, Delaware, Hawaii, Massachusetts, Maryland, New Hampshire, Nevada and Rhode Island). Using best subsets regression (a statistical technique for estimating values to replace missing data), we also imputed poverty level for use in the multivariable regression models in the approximately 9,000 cases in which this information was missing from the NSCH.¹⁹

Study design and data analysis. We analyzed data using statistical software (Stata software, version 8.0, Stata Corp., College Station, Texas). To account for the complex survey design, we used Stata survey commands and the population weights provided in the data files when generating population level estimates and standard errors. We conducted descriptive analyses, including bivariable tests of the association between explanatory covariates and our outcome (that is, having dental insurance). In addition, we relied on multivariable logistic regression to identify factors independently associated with having dental insurance (Table 1). We developed a second multivariable logistic model for the outcome of having had a PDC visit within the previous 12 months. This model was used to determine the independent association between having had a PDC visit in the previous 12 months and having dental insurance (Table 1).

We built on the second model to assess the effect of dental insurance and race/ethnicity on PDC use, an area of particular interest based on our observations that certain racial/ethnic groups had a high likelihood of having dental insurance and a low likelihood of PDC use and vice versa. To this end, we repeated the second logistic regression model, this time including an interaction term between race/ethnicity and type of dental insurance (private, public or uninsured). We estimated a linear combination of coefficients to determine the odds ratio for PDC for the various racial/ethnic groups with each of the three categories of dental insurance.

	RESULTS

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Dental insurance. The 102,353 children for whom data were collected represented 72.7 million children nationally, on a weighted analysis. The dental insurance question was answered by 98.1 percent of respondents. Overall, 77.2 percent of children had insurance that helps pay for any routine dental care. With regard to lack of insurance, 22.6 percent of U.S. children were uninsured for dental care and 8.6 percent were uninsured for medical care, for a ratio of 2.6. Among children whose parent or guardian reported that they lacked dental insurance, 2.9 million were potentially eligible for public dental insurance—either SCHIP or Medicaid—based on the income eligibility criteria of their state of residence, and 8.3 million had private medical insurance but no dental insurance. Eighty-eight percent of children without dental insurance (14.1 million children) resided in households in which at least one adult worked 50 or more weeks per year.

We found surprisingly little difference in dental insurance rates across ages: the smallest percentage of children with dental insurance consisted of those younger than 1 year (70 percent), and the highest percentage of children consisted of 9-year-olds (82 percent). The results showed more variation in public dental coverage proportions across ages. Among children 5 years and younger with dental insurance, 35.1 percent had public dental insurance compared with 26.7 percent of children older than 5 years. We also found variability between states with regard to the proportion of children with public dental insurance (Figure 1) and those who were uninsured for dental care (Figure 2).

View larger version (65K): [in this window] [in a new window]   Figure 1. Percentage of children with public dental insurance, by state.

View larger version (70K): [in this window] [in a new window]   Figure 2. Percentage of children uninsured for dental care, by state.

View larger version (45K): [in this window] [in a new window]   Figure 3. Percentage of children older than 1 year with a reported preventive dental care visit in the previous 12 months.

View larger version (47K): [in this window] [in a new window]   Figure 4. Adjusted odds ratio of having had a preventive dental care visit in the previous year, by type of dental insurance and race/ethnicity. SCHIP: State Children’s Health Insurance Program.

	DISCUSSION

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Enactment of SCHIP and associated Medicaid expansions in the previous 10 years resulted in greater proportions of children insured for both dental and medical care. However, Medicaid and SCHIP are, for the most part, the only insurance programs that cover both medical and dental care. Employment-related dental benefits do not consistently accompany the more commonly offered medical benefits, a continuing phenomenon that seems to largely explain why the proportion of children with dental insurance still substantially lags behind the proportion of children with medical insurance.

We found that 72 percent of U.S. children in 2003–2004 had at least one reported PDC visit in the previous year. Only a few studies have separated out PDC visits from dental visits in general. Using data from the 1996 Medical Expenditure Panel Survey, Watson and colleagues²⁰ reported that 38 percent of children overall and 20 percent of children living in households with incomes at or below 200 percent FPL had a PDC visit in the previous year. More recently, Kenney and colleagues⁸ conducted a study of low-income children and found that 71 percent of children living in households with incomes at or below 200 percent FPL had at least one reported PDC visit in the previous year. In a 2000–2001 study of 2,642 Maryland schoolchildren, Macek and colleagues²¹ found that 71 percent of children overall and 54 percent of children eligible for free lunch were reported by their parents to have had a dental prophylaxis visit in the previous year. We relied on data from all 50 states and Washington, as well as a sample size at least an order of magnitude larger than those in these other studies, and we found that 62.5 percent of low-income children had a reported PDC visit in the previous year. This proportion is within the range reported by other recent pediatric-specific studies in which similar survey methods were used.

Underrepresented groups. Certain groups continued to be underrepresented in their receipt of PDC after we adjusted for confounders. These included children aged 1 through 5 years, who are black or multiracial, who lacked dental insurance, who lacked a personal physician, who were living in households with incomes below 400 percent FPL (with a progressively negative impact as the household income dropped), who lived in non-MSA areas or states, or who were born outside the United States.

Significantly fewer children with public insurance had a PDC visit, but on adjusted analysis, the likelihood of having had a PDC visit for publicly insured children was essentially equivalent to that for children with private insurance. This is not to diminish the widely reported difficulties that publicly insured children face in obtaining needed dental care.^22–26 What this does mean, however, is that it is not public insurance per se but other characteristics that are associated with being publicly insured, such as the percentage of a state’s dentists participating in Medicaid and the myriad challenges accompanying poverty, that appear to have greater influence over whether a child has had a recent PDC visit. Thus, improving dental care use among publicly insured children will require more than mere Medicaid reform. Instead, interventions must be aimed broadly at the multiple barriers, both within the dental office and the family, that interfere with low-income children’s accessing dental care.

PDC for young children. The majority of children, even young children, had dental insurance. Vargas and colleagues² found that 67 percent of children 5 years and younger had dental insurance in 1995, which is only slightly lower than our result of 72 percent. Yet, we were surprised that the majority of infants had dental insurance (70 percent had dental insurance and 42 percent had private dental insurance). Although public dental insurance theoretically is available to eligible children from birth, we had hypothesized that parents with the option of purchasing dental coverage through their employers would delay doing so for their children until they were somewhat older. In contrast to the percentage of those insured, only a small proportion of U.S. children younger than 3 years used PDC services, despite the recommendation of the ADA⁵ and the American Academy of Pediatric Dentistry²⁷ that the first dental visit occur by 1 year of age.

Low rates of preventive care in young children are of particular concern, given a 2005 CDC report indicating that young children are the only U.S. population group that has experienced recent increases in caries levels.²⁸ This discrepancy between very young children with dental insurance and those who had received a PDC visit suggests that other factors—such as cultural norms regarding the first dental visit, the perception that insurance is for problems and not prevention, and the availability of dentists willing to treat very young children—may be contributing to the low proportion of young children with a PDC visit.

Race/ethnicity. Race/ethnicity was an important effect modifier in the relationship between dental insurance coverage and receipt of care. Of all the racial/ethnic groups in this study, Hispanics/Latinos had the lowest proportion of PDC visits. This represents a real disparity that deserves attention. However, as we seek to understand the complex interplay of factors underlying disparities, results of multivariable analyses can be illuminating. After controlling for other variables that also influenced access to PDC, we found that Hispanic/Latino children’s likelihood of having had a PDC visit was not statistically distinguishable from that of white children. In fact, Hispanic/Latino children with public insurance were more likely to have had a PDC visit than were publicly insured white children. Thus, it appears that other factors that are more common among Hispanics/Latinos, such as being born outside the United States (and thus not being eligible for most public insurance programs), affect their receipt of PDC, rather than being Hispanic/Latino in and of itself.

Black and multiracial groups. In contrast, black and multiracial groups had the highest proportion of children with dental insurance, albeit the majority were publicly insured. Vargas and colleagues² reported similar results based on 1995 data. However, in 1995, as with our results, blacks had the lowest likelihood of having had a PDC visit on adjusted multivariable analysis (significantly lower than that for whites and Hispanics/Latinos). These findings and the persistence of an effect on adjusted analysis suggest issues intrinsic to the black community. Among black children with private dental insurance, the adjusted odds of having had a PDC visit were more than 40 percent lower than they were for white children. We observed this phenomenon even after controlling for household income, making the higher out-of-pocket costs associated with private dental insurance less of an issue. These findings raise questions about the sociocultural perceptions of PDC among blacks and about the availability of professional dental care in neighborhoods where black children reside. Relative to people in other racial and ethnic groups in the United States, blacks of all socioeconomic strata are more likely to live in segregated communities²⁸ where professional dental care may be less accessible.

Need for greater dental insurance coverage. Although it is clear that the factors underlying PDC are complex, increasing dental insurance availability should, nevertheless, be a priority. Those lacking dental insurance were less than one-half as likely to have received PDC, even after we controlled for income and other socioeconomic variables that also influence access to care. Ultimately, the goal of professional PDC is improved oral health, and dental insurance should mediate the achievement of this goal. Indeed, more than 20 years ago, the RAND Health Insurance Experiment confirmed the importance of affordable dental insurance to oral health when investigators found that reducing cost-sharing for dental services improved oral health, especially for subgroups of the population with the poorest oral health.²⁹ Among young children in the RAND study, those insured by a plan without cost-sharing had significantly less caries at the end of the study than did children covered by the cost-sharing plans; this benefit was greatest for middle- and low-income children.³⁰

To increase the proportion of children with dental insurance coverage, both SCHIP and employer-based dental benefits should be targeted. We estimate that by standardizing SCHIP dental coverage and income eligibility such that all near-poor children are covered (that is, provide SCHIP dental benefits across 50 states for children with household incomes up to 200 percent FPL who are currently outside of the Medicaid income eligibility range and who are uninsured for dental care) would decrease the number of children uninsured for dental care by 1 million.

Four states with separate SCHIP programs (Idaho, Oregon, Montana, North Dakota) and five states with combined SCHIP-Medicaid programs (Alaska, Nebraska, South Carolina, Tennessee, Wisconsin) have income eligibility limits below 200 percent FPL.³¹ In addition, 2.9 million children were reported by their parents to have SCHIP or Medicaid but were said to be uninsured for dental care (excluding SCHIP-eligible children in Delaware, because dental care is not covered under SCHIP in that state). It is likely that the majority of these children do have public dental insurance but their parents are unaware of it. Another 8.2 million children have private medical insurance but are uninsured for dental care. Our data do not enable us to ascertain the degree to which employment-related dental benefits are available for these children but are not accepted by their parents. Nevertheless, the United States could substantially diminish the disparity in the proportion of children uninsured for dental care relative to medical care if the following were to occur:

– SCHIP dental benefits were standardized such that all near-poor children without dental insurance would be covered;

– all eligible families with public health insurance were informed, when they signed up for Medicaid or SCHIP, that their child also had dental coverage;

– children with private medical insurance also had dental coverage

Although the cost of providing dental insurance to an additional 12 million children would not be inconsequential, dental coverage is relatively inexpensive compared with medical insurance. In the late 1990s, actuarial estimates of the cost to provide comprehensive preventive, diagnostic, restorative and select orthodontic care for all SCHIP-covered children ranged between $17 and $20 per child per month.³² A 2006 report for the Virginia State Proposed Model Insurance Product estimated that the premium cost for private dental insurance for small-business employees at 100 to 300 percent FPL would be $26 per month for the employee and $75 for the employee and his or her family.³³ If an affordable "dental only" insurance program were available from states, other organizations or insurance companies, this would provide an opportunity for dental coverage for those who receive only medical insurance benefits through employment.

Study limitations. Certain limitations bear mention. In this survey, PDC visits and insurance status were determined via parental reports, which, as Macek and colleagues³⁴ have discussed, may be subject to error or bias. Parents may not recall events accurately over a period as long as one year, or they may overestimate the frequency of their children’s dental visits to provide more desirable responses. In addition, the phrasing of the NSCH PDC question encompassed a broad spectrum of possibilities for PDC. Our results should not be taken to mean that children who had a PDC visit necessarily had a usual source of dental care or a dental home.

In addition, other limitations are inherent to large surveys, in which a relatively limited number of variables are available. There may be unmeasured variables that also affect the likelihood of having dental insurance or receiving PDC. For example, we had to rely on indirect measures of community-level constraints on access to dental care (such as the proportion of dentists participating in Medicaid or SCHIP), and these may not adequately reflect some families’ experiences in seeking PDC. We also had no way of assessing the quality of a particular dental insurance plan or determining if a child had dental insurance for only part of the year; thus, we may have overestimated the effect and prevalence of dental insurance. Finally, this report focused on the impact of dental insurance on PDC visits; a number of other issues must be considered in efforts toward improving access to professional dental care for children.

	CONCLUSION

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Dental insurance, whether public or private, is associated with a higher likelihood of receiving PDC for U.S. children. Despite recent increases in the number of children with dental insurance, 2.6 times as many children are uninsured for dental care relative to medical care.

Although black and multiracial children and very young children have relatively high rates of dental insurance coverage, their receipt of PDC is disproportionately low. Myriad other factors influence access to, and use of, PDC. Nevertheless, expanded availability of dental insurance offers an important and relatively feasible step toward reducing disparities in oral health that exist in the United States. We offer specific recommendations to expand the availability of dental insurance coverage for U.S. children.