Barriers to dental care for Medicaid enrollees have been well-documented.^16–23 These barriers may be related specifically to aspects of the Medicaid program, such as low dentist participation, resulting, in part, from lower reimbursement rates and perceived programmatic challenges. There also are individual factors associated with a lower-income population such as less understanding of the importance of preventive dental care that can delay or stop enrollees from accessing dental care.²⁴ Privately insured enrollees can face some of the same issues, such as finding a dentist who accepts their insurance plan and understanding the importance of preventive dental care. The presence of private insurance, however, generally has been found to significantly increase access to dental care.^6–14

Medicaid (Title XIX) is the largest public dental insurance program in the country; more low-income people receive dental care through Medicaid than any other program.²⁵ Medicaid is a part-federal, part-state program administered by the federal Centers for Medicare and Medicaid Services. While dental care is a required service for children enrolled in Medicaid, it is an optional service for adults; states can determine the types of dental services, if any, they will cover for adult enrollees. Eligibility for adults without disabilities in Iowa’s Medicaid program in fiscal year 1998 was quite limited in general, adults had to be in households with incomes at or below 37 percent of the federal poverty level.

Medicaid (Title XIX) is the largest public dental insurance program in the country.

In one of the few studies comparing the utilization of dental services of a privately with a publicly insured population, Medicaid enrollees were found to be the least likely to have had a dental visit during the year.²⁶ Fifty-nine percent of those with private insurance reported having a dental visit in the previous year, compared with 42 percent of those without dental insurance and 32 percent of those in Medicaid.

In our study, we compared the dental care utilization of two insured adult populations: those insured by Delta Dental Plan of Iowa and those publicly insured through the Iowa Medicaid program.

Delta Dental Plan of Iowa is the largest private dental health insurance plan in Iowa, and it provides dental benefit coverage through employers to nearly 650,000 members annually.²⁷ It offers more than 200 plan options to Iowa employers with varying benefit packages based on employers’ interests. Delta Dental Plan of Iowa primarily offers a fee-for-service product with limited preferred provider organization options and no risk-based managed care plans.²⁷

The Iowa Department of Human Services (IDHS) administers the Iowa Medicaid program. The Iowa dental Medicaid program is an entirely fee-for-service program without any dental managed care options. Dentists are reimbursed on a fee schedule established by IDHS based on annual appropriations from the state legislature. In fiscal year 1998, Medicaid fees were approximately 50 percent of usual, customary and reasonable fees in Iowa (Ms. Cathy Coppes, Iowa Department of Human Services, written communication, June 2002). During the time of this study, the Iowa Medicaid program included a comprehensive dental benefit package for adults covering all preventive and routine restorative services, endodontic and oral surgery services, and limited prosthodontics.

Both Delta Dental and Medicaid are statewide programs with overlapping but not consistent dental provider networks. About 90 percent of all Iowa dentists participate as members of the Delta Dental provider panel (Dr. Ed Schooley, dental director, Delta Dental of Iowa, written communication, June 2002). About 83 percent of all Iowa dentists were signed up as Medicaid providers in 2001, with 76 percent submitting least one dental claim for care to a Medicaid enrollee during fiscal 2001 (Ms. Cathy Coppes, Iowa Department of Human Services, written communication, June 2002).

In this study, we evaluated differences in use of dental services and the demographics of the people using services for these publicly and privately insured populations. We paid special attention to differences in the receipt of tertiary care services such as endodontic therapy and tooth extractions.

	METHODS

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We used Iowa Medicaid and Delta Dental claims files that we obtained directly from both insurers to evaluate the utilization of dental procedures for these two adult (21–64 years of age) populations. Our cross-sectional analysis used data from fiscal year 1998 (July 1, 1997, to June 30, 1998). To be included in our analysis, adult Medicaid enrollees had to be eligible for Medicaid for the entire year through the Temporary Assistance for Needy Families (TANF) program. We considered the continuously enrolled TANF population to be most similar to a privately insured population in that the group included relatively healthy young adults. We excluded enrollees eligible through the Medicaid Supplemental Security Income and Medically Needy programs since they were eligible, in part, owing to poor health status, institutionalization (for example, low-income long-term care facility residents) or both. We used data for all adults enrolled in Delta Dental of Iowa in fiscal year 1998 in our analyses.

We used eligibility files for the Iowa Medicaid program to determine the number of adults, by age and sex categories, who were eligible for the program. This number became the denominator used to calculate the dental care utilization rates for Medicaid enrollees. Delta Dental’s enrollment files were not available for fiscal year 1998, though the total number of Delta Dental enrollees was. We then applied the proportion of Delta Dental enrollees in each age/sex category in fiscal year 2001 (the only year in which this information was available) to the total number enrolled in fiscal year 1998 to estimate the number of enrollees in each age and sex category for the denominators. Applying the proportion in each age/sex category from 2001 to the total number of enrollees in fiscal year 1998 was considered appropriate because Delta Dental did not experience significant changes in their customer populations between fiscal year 1998 and fiscal year 2001; thus, Delta Dental did not believe there were differences in the age/sex distribution of their insured population between those years (Dr. Ed Schooley, dental director, Delta Dental of Iowa, written communication, June 2002).

We used insurance claims files to calculate the numerators for the utilization rates in both populations. We identified enrollees as having a dental visit during the year if they had a claim that included any dental procedure code from Current Dental Terminology-2 (CDT-2).²⁸ The procedure codes we used to categorize enrollees as having had a particular type of service were the most common CDT-2 codes used by both Delta Dental Plan of Iowa and Iowa Medicaid in 1998 (that is, preventive codes 01000–01999, restorative codes 02000–02999, endodontic codes 03000–03999, periodontic codes 04000–04999 and oral surgery codes 07000–07999). We determined the number of enrollees receiving each type of service by aggregating the claims using a combination of individual identification numbers and dates of service.

To evaluate tertiary care service use, we limited endodontic and oral surgery procedures to procedure codes for endodontic therapy and non-surgical tooth extractions, as these are the procedures most related to poor oral health status. We did not include endodontic therapy in primary teeth, as this study focused on adults. Because teeth numbers were not available in the Delta Dental data set, tooth location was available only for endodontic therapies, as the procedure codes made such identification possible (for example, 03310 anterior, 03320 bicuspid, 03330 molar).

	RESULTS

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Table 1 shows that 69.3 percent of Delta Dental adult enrollees had used dental services in fiscal year 1998 compared with 27.2 percent of Medicaid adult enrollees. For those with a dental visit, Medicaid-enrolled adults were primarily female (83.0 percent), while the Delta Dental population was more closely divided between men and women (43.3 percent and 56.7 percent, respectively). Those enrolled in Delta Dental who used dental services were older, with 84.4 percent of users being 31 years of age or older In the Medicaid population, 54.3 percent of users were 30 years old or younger. Ninety-six percent of the Medicaid population was 45 years old or younger.

	DISCUSSION

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These differences also emphasize the importance of factors other than insurance coverage that can affect dental care utilization (for example, perceived need for care, ability to access dental care and attitudes toward the importance of dental services). If insurance coverage alone were the most significant barrier to dental treatment, one would expect similar utilization rates for these two insured adult populations. The dollar cost for many people with Delta Dental insurance actually was higher than for Medicaid enrollees when we considered coinsurance rates for select services; for example, there is 50 percent coinsurance for prosthodontics with some policies. The cost for adult Medicaid enrollees was the $3 copayment per visit and out-of-pocket costs for any desired noncovered services. In reality, however, a $3 copayment for a low-income person can be a larger percentage of his or her disposable income than the cost of a restoration for a higher-income insured adult with a private insurance policy that has a 50 percent coinsurance rate.

The larger younger adult population in the Medicaid program was related primarily to the fact that women of childbearing age are the predominant adults who are eligible for Medicaid through the TANF program. While it might be expected that the significantly younger age distribution of the Medicaid enrollees would lessen the receipt of tertiary care services, this was not true from a population perspective as a whole. Medicaid enrollees were more likely to undergo endodontic therapy and extractions than Delta Dental enrollees, with the proportion of young adults receiving these services being the age group that was most different from those with private insurance. Women were more likely than men to receive dental care in both populations. Among older enrollees, women were more likely to undergo endodontic therapy, whereas men were more likely to have a tooth extracted.

Women were more likely than men to receive dental care in both the privately and publicly insured populations.

Although the data are specific for care provided in a single state, the trends we noticed are likely to be found in most states. The disparity in the use of dental services between these two adult populations actually may be conservative relative to other states, considering that Iowa’s Medicaid program provided comprehensive adult dental care coverage at the time of this study (Iowa eliminated coverage for some adult dental services such as posterior endodontic therapy and crowns in 2002). The differences in the receipt of tertiary care dental services are likely to be greater in states with less generous dental Medicaid benefit packages for adults. As states like Iowa reduce or eliminate their benefit packages for adults, low-income patients will have fewer options other than extractions for teeth that have extensive caries.

In addition, because Medicaid enrollees are more likely to be enrolled for only part of a year, as a group they are going to have less opportunity to try to access dental services while covered by insurance. If only those people who were eligible for the entire year were included in this analysis, the percentage who had received a dental service would have increased. However, this also would have increased the percentage of enrollees who underwent endodontic therapy and the percentage who received extractions, making their use of tertiary care services even greater compared with the privately insured population. Partial-year coverage for many Medicaid enrollees, combined with the difficulty finding a dentist who accepts Medicaid patients, presents a significant barrier to Medicaid enrollees’ having a dental home where they can seek primary and preventive dental services from the same dentist. The ultimate improvement in oral health status in this population of low-income adults will hinge in large part on strengthening the dentist-patient relationship such that they can feel that they have a regular source of dental care.

From a clinical perspective, the significantly greater overall receipt of tertiary care services by enrollees in the Medicaid program indicates a lower oral health status at the time care is sought. Few people would elect to undergo endodontic therapy or tooth extraction unless a dentist told them these services were needed. Medicaid enrollees, however, had a 300 percent greater rate of tooth extractions compared with endodontic therapy. This could be related to several factors.

It is possible that more Medicaid enrollees had teeth so cariously involved that they were non-restorable even with endodontic therapy—an indication of the severity of the enrollees’ oral health problems. Many people in this population may be less likely to seek care for minor caries and may wait to seek treatment until their teeth are more extensively carious or there is pain. This would result in fewer restorative treatment options or endodontic therapy and, thus, more extractions. In addition, there may be a higher rate of periodontal disease in this population, resulting in more people who may have lost for periodontal reasons teeth that could not have been saved with endodontic therapy. There may be more people for whom losing a tooth was less a problem than the multiple visits necessary to save it.

The availability of specialists could affect the final treatment. Data from a 1993 study in Iowa shows that while 77 percent of oral surgeons were accepting all-new Medicaid patients in Iowa, only 6 percent of endodontists fully participated.¹⁸ This may result in Medicaid patients’ finding it easier to have a tooth extracted than to find a dentist to complete endodontic therapy.

Some dentists could be biased toward extracting a tooth for a Medicaid-enrolled patient. They may not be interested in completing endodontic therapy involving a post and core and crown for a person who they believe may not really value the treatment or is less compliant, and for whom they ultimately will receive lower reimbursement for their efforts.

There are advantages and disadvantages to using administrative data for a dental care utilization study. Using information directly from the insurer eliminates the need to rely on people’s memories regarding past use of dental services, as is the case in surveys. Since all submitted claims for services can be evaluated, errors that can be introduced through the sampling processes often used when conducting surveys and the potential response biases that can be introduced are eliminated. On the other hand, insurance claims data are collected for the purpose of paying for services and are not intended to be used for research. Thus, differences in how dentists code individual procedures or whether they even submit a claim introduces limitations into the use and interpretation of administrative data. For such analyses, differences in how a dental procedure is coded by dentists may be minimized by categorizing procedures according to service areas (for example, preventive, routine restorative) as we did in our study. The lack of diagnosis codes in dentistry also eliminates the possibility of knowing why a treatment was given from administrative data alone.

	CONCLUSIONS

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Dental care utilization rates for Iowa Medicaid enrollees were significantly lower than those for the privately insured Delta Dental Plan of Iowa enrollees within the same state market area. The demographics of the two populations differed considerably in terms of age and sex. The Iowa Medicaid population was younger and predominantly female compared with the Delta Dental Plan of Iowa population. The utilization rates of endodontic and extraction services show that when enrollees do access care, Medicaid enrollees receive endodontic therapy and extractions at a higher rate than the privately insured Delta Dental enrollees, even though they are much younger as a group. This may signify that they have a poor health status and a greater need for endodontic and extraction services than Delta dental enrollees. These utilization patterns could reflect a problem enrollees have accessing care or a less-perceived need for oral health care, causing a delay in attempting to seek dental services.