Intellectual disability (ID) is significantly associated with poor oral health (USDHHS, 2000). Although recent advances in medical care have contributed to a substantial increase in the life expectancy of individuals with ID (Bittles et al., 2002; Janicki, Dalton, Henderson, & Davidson, 1999), dental care remains an unmet need (Waldman & Perlman, 2002). A recently published systematic review of studies confirmed the existence of gaps in dental care among people with ID within different age groups (Anders & Davis, 2010). Individuals with ID are more likely to receive a lower quality of dental care, or are less likely to have had a preventive dental visit, compared with individuals without ID (Charles, 2010; Chi, Momany, Kuthy, Chalmers, & Damiano, 2010; Reichard, Turnbull, & Turnbull, 2001).

A study among children aged 3–17 years show older age, better access to dental health professionals, higher educational and family socioeconomic status, and experiencing a favorable interaction with the medical system, have all been associated with better preventative dental care use, irrespective of their ID status (Chi et al., 2010). On the contrary, other studies have shown that increasing dental care costs, lack of dental insurance or financial resources to pay for treatment, access to information, and willingness and training among dentists treating children with disabilities have negatively influenced dental care (Dasanayake, Li, Chhun, Bronstein, & Childers, 2007; Schultz, Shenkin, & Horowitz, 2001; Stiefel, 2002; Wolff, Waldman, Milano, & Perlman, 2004). Although these factors might also influence dental care across different age groups, understanding of the predictors and barriers for dental care among young adults with ID is limited.

One of the key limiting factors for dental care access among young adults is that, in the majority of states, Medicaid dental coverage is terminated when an individual attains 21 years of age (Centers for Medicare and Medicaid Services, 2011). In recent decades, a shift toward inclusion of individuals with ID into community-based or independent residential settings has occurred, which has led to disruption of routine dental care services available previously within institutional residential settings (Dwyer, 1998). Thus, as young adults are transitioning from pediatric to adult dental care, those with ID are particularly vulnerable to dental problems. Dental care among children with ID until age 18 years has received much attention; however, information specific to young adults in the earlier part of their young adulthood (ages 21–25 years) is lacking. Using a population-based study, we examined the frequency of dental visits and selected associated factors that promote or limit dental visits among young adults with and without ID. The study also examined the frequency of dental care on the basis of severity of ID and co-occurrence of other selected developmental disabilities (DDs).

Our study included all 244 young adults with ID identified by MADDSP, with or without other co-occurring DDs and 124 young adults without ID or other DDs. In the final sample of young adults with ID, 48% (n = 117) had isolated MID; 30% (n = 73) had isolated MPID; and 22% (n = 54) had ID and at least one co-occurring DD. Across all severity levels, young adults with ID differed significantly from those without any ID by demographic characteristics, dental visits, dental service use, and dental health.

Young adults with ID were more likely to be male, black, aged 24–25 years, less than high school educated, unemployed, not receive vocational services, live in a nonindependent setting, and have limitations in ADLs and IADLs, compared with young adults without ID (Table 1). Similar differences were identified between young adults with isolated MID, compared with young adults without ID; but additionally, young adults with isolated MID were significantly more likely to receive income-dependent services, compared with those without. The third group, young adults with isolated MPID, were more likely to be black, aged 24–25 years, less than high school educated, unemployed, not receive vocational services, live in a nonindependent setting, and have limitations in ADLs and IADLs, compared with young adults without ID; similar differences were noted for the group of young adults with multiple ID, compared with young adults without ID, also demonstrating that young adults with multiple ID were likely male, compared with those without ID (Table 1).

As children with ID reach young adulthood, they often face a myriad of challenges related to receipt of adequate and integrated health and education supports while transitioning from pediatric to adult services (Chambers, Rabren, & Dunn, 2009; Cobb & Alwell, 2009). Unfortunately, when priorities for overcoming these obstacles are identified, dental care is often overlooked because of more pressing needs (Waldman & Perlman, 2002). Given that ID is one of the most common DDs, affecting approximately 1%–2% of school-aged children, attention is needed to better understand the frequency and correlates of dental care within this population as they develop into young adults. In our study, occurrence and factors associated with dental care visits during a year were explored for the first time among a population-based sample of young adults with and without ID. We determined that young adults with ID were significantly less likely to visit the dentist during a year, compared with their unaffected counterparts. Sociodemographic and dental care variables, including sex, race/ethnicity, education, receipt of vocational services, limitations in ADLs, type of dental care insurance, and having toothache during the 4 weeks before the interview (which might be an indicator for poor dental care in itself) were identified as significant factors that promoted or limited dental care among young adults.

Access to dental care is commonly defined as an ability to obtain and make use of dental services (Guay, 2004). Dental care use is frequently measured by asking respondents if they visited a dentist at least once during the previous year, with national estimates demonstrating that on average, individuals in the general population visit the dentist approximately twice a year (USDHHS, 2000). The lack of existing research on dental care among young adults with ID limited the comparison of our findings on frequency of dental visits in a year. Nevertheless, when compared with studies based on children aged ≤18 years with ID that examined the percentage of children reporting at least one dental visit during a year, our study finding of 45% was within the same range (39%–54%) (Chi et al., 2010; Macek, Edelstein, & Manski, 2001; Soni, 2011).

Selected demographic predictors were explored and identified as significant predictive factors for dental visits among young adults in our study, and these differed by the occurrence and severity of ID. These factors further varied by the outcome (one versus two dental visits per year). We determined that among young adults with ID, males were at a significant risk of not visiting a dentist. Other studies among children with ID aged ≤18 years or younger (Macek, Edelstein, & Manski, 2001) and youth and adults with ID aged 18–44 years (Pradhan, Slade, & Spencer, 2009) did not find an association between sex and dental care visits. A racial/ethnic disparity in reported dental care visits was noted in the unadjusted analysis of our study, but did not remain significant after adjusting for other cofactors. Other studies reported racial/ethnical disparities in dental visits where white non-Hispanic children with or without ID were more likely to have at least one dental visit in a year, compared with black non-Hispanic children (Chi et al., 2010; Macek et al., 2001; Soni, 2011). Because race/ethnicity is often used as a proxy for SES, we explored the role of competitive employment and educational attainment to further assess this association.

Although dental care visits in association with educational and employment status of young adults have not been examined previously, higher educational and SES of the family has been reported to predict dental care use among children in the general population (Chi et al., 2010; Soni, 2011). Results from our adjusted analyses revealed having less than high school education is a significant predictor for not visiting a dentist at least once or twice per year among young adults with ID and once per year among young adults with isolated MID. We also identified employment status as a significant predictor for not visiting the dentist at least once per year, particularly for young adults with isolated MID, but the association was not significant after adjusting for other cofactors. Although in our study only 36.5% of young adults with ID were reported to be employed, this finding converged with that from another nationally representative study of adolescents and young adults with disabilities, where 31% of subjects with ID had obtained employment (Carter, Austin, & Trainor, 2011).

We determined that young adults with ID who received vocational services were more likely to visit a dentist at least once or twice per year. Further, young adults with isolated MID were more likely to visit a dentist at least twice per year if they received a vocational service. A study using the National Health Interview Survey (NHIS) data reported that 72% of working adults aged 18–65 years who had self-identified as having an ID received at least one or more vocational services during their lifetime (Olney & Kennedy, 2001). Receipt of vocational services was greater among those with ID if they were males, aged 25–44 years, white, not living independently, high school educated, and had limitations in ADLs and IADLs (Olney & Kennedy, 2001). In our study, 59% of young adults with ID had received a vocational service; and among those, the majority was male, black, high school educated, and had limitations in ADLs. The association between these predictive demographic factors for the use of vocational services among young adults with ID might explain, in part, the association we identified between vocational services and dental care visits. Further, young adults receiving vocational services might differ from their counterparts with respect to increased parental supervision, ability to access health care and personal grooming skills for seeking employment (M. Blanding, Atlanta Regional Office for Vocational Rehabilitation, personal communication, February 22, 2012).

Living arrangements or residential factors have been examined in relation to dental care use among individuals with ID. A Swedish study compared dental health status of children with severe ID to that of control subject children and reported that children with severe ID living in an institutionalized setting reported better access to dental care and had a lower prevalence of caries, compared with children with ID living in a community-based setting or control subject children (Forsberg, Quick-Nilsson, Gustavson, & Jagell, 1985). Adults with ID were also significantly less likely to have a dentist and rely on community dental services if residence was in a noninstitutionalized setting, compared with their counterparts living in an institution (Tiller, Wilson, & Gallagher, 2001). Freedman and Chassler (2004) reported that adults with ID living with parents or relatives were least likely to visit a dentist within the previous 6 months of the study (72%), compared with those living in community residences (82%) or institutional facilities (82%). In our study, living arrangement was not associated with and dental care visits among young adults with or without ID. The association between residential factors and dental care use among individuals with ID is complicated by correlated factors, including but not limited to, severity of ID, co-occurring conditions, employment, and dental insurance. Further exploration of these associations is warranted.

Our finding that young adults with ID with limitations in ADLs were more likely to have at least one or two dentist visit per year, compared with young adults with ID without limitations in ADLs, needs further exploration. Limitations in ADLs among persons with severe ID have been reported to influence their ability to seek assistance for their dental needs in one study from Japan (Chiwata & Takeda, 2007), but this association was based on a limited sample of individuals. Also, the association between ADLs among persons with ID and dental care frequently can be interrelated with presence of other co-occurring DDs (Harries, Guscia, Nettelbeck, & Kirby, 2009). No other studies among young adults with ID have examined the association between ADLs or IADLs and dental care use for comparison. It is possible that young adults with ID, particularly with co-occurring conditions that have ADLs or IADLs, may receive assistance from caregivers to perform daily activities. This may also increase the likelihood of better dental care and regular receipt of dental services. Our evidence of activity limitations as significant mediators between ID and dental care highlight an area for intervention that might improve dental health. Examining the role of caregivers among young adults with ID with limitations in ADLs and IADLs may provide additional insight into these findings.

Dental care insurance plays an important role in one’s ability to obtain dental services regardless of disability status. Individuals without dental insurance, particularly those from lower socioeconomic backgrounds, are less likely to visit a dentist (Guay, 2004). For Medicaid recipients, reimbursement for all dental services is mandated for children and adolescents from birth to age 21 years (CMS, 2011). Despite this easily available reimbursement mechanism, only 20% of Medicaid-eligible children receive preventative dental care by age 20 (Waldman & Perlman, 1997). Medicaid reimbursements for dental services become elective after age 21, where each state covers only selected dental services for eligible adults, some ranging from comprehensive care to just emergency services (Waldman & Perlman, 2004). In Georgia, Medicaid reimbursements are available for eligible adults, but restricted to emergencies (e.g., tooth extractions [GDCH, 2011]). Approximately half of young adults with ID in our study had Medicaid as their dental insurer, whereas one-fourth had HMO or private insurance, and another quarter paid for dental care with their own or borrowed money. Denial of care among those with Medicaid is also a problem. Surveys conducted in Alabama (Al Agili, Roseman, Pass, Thornton, & Chavers, 2004) and Tennessee (Valet, Kutny, Hickson, & Cooper, 2004) determined that families of special needs children with Medicaid were less likely to visit a dentist, compared with their counterparts with private insurance because of denied access.

The association between having a toothache within 4 weeks before the interview and receipt of dental services among young adults with and without ID was determined as significant for at least one dental visit during a year among young adults with ID and isolated MID. One of the reasons for this association might be the higher incidence of toothache among those with ID (Scott, March, & Stokes, 1998), and that young adults with ID are highly vulnerable to lack of adequate preventative dental care, which might be a result of the absence of dental insurance. The toothache might also serve as an indicator of poor dental care. Future studies may have to prospectively evaluate this association taking into consideration the temporality of dental care and dental problems among young adults with ID. The frequency and characteristics of acute dental conditions should be explored further among young adults to better understand their dental problems, timely preventative care, and therapy.

The role of severity of ID and presence of other co-occurring DDs on dental care use has not been explored among young adults. Institutionalization might have served as an important proxy for ID severity and presence of co-occurring DDs. However, recent shifts in community-based living and social integration of individuals with ID makes studying dental care visits challenging, particularly among young adults with mild and moderate ID. As more people with ID are integrated in the community, a greater gap might exist in meeting oral health needs and visiting a dentist, compared with those living in institutional settings (Tiller et al., 2001).

One of the strengths of our study is the population-based design and presence of interview questions related to dental care. The structured telephone interviews, conducted by trained interviewers, offered the opportunity to examine key dental care characteristics among young adults with and without ID for the first time. The MADDS surveillance data improved the diagnostic specificity and more complete ascertainment of young adults with ID, compared with other studies and allowed evaluation of dental care by severity of ID and co-occurring DDs. The questionnaire assessed crucial demographic, lifestyle, and health care variables, allowing multivariable models with potential co-factors. Findings from the study provide valuable information and can help generate new hypotheses for future investigation.

Our study was also subject to limitations. The MADDS Follow-Up cohort might not have represented the more current generation of young adults. The interview responses may have potential recall error and responses related to dental visits cannot be validated. Our study was unable to examine additional factors that might have contributed to disparities in dental care visits. Only 5% of young adults without ID in our study reported Medicaid as their primary source of dental care insurance, compared with 25% of Medicaid enrollees among the general population (Vivier, 2005). Thus, Medicaid dental insurance prevalence in the current study might not be representative of general population. The association between having Medicaid insurance and reporting two or more dental care visits per year by young adults with and without ID in our study should be interpreted with caution. The cross-sectional analysis limited our ability to analyze temporality in some of the observed associations, for example, it was hard to determine the accurate role of toothache during the period prior to the interview as an indicator for receipt of dental care, considering the possibility that the toothache in itself may be a result of poor dental care.

Our results have implications for national objective planning regarding dental care, both among individuals with and without ID. The oral health objective of Healthy People 2020 is to increase the proportion of children, adolescents, and adults who use the dental care system (USDHHS, 2011). In particular, the 2008 National Dental Summary report proposed to raise the proportion of children, adolescents, and adults who use the dental care system within a year from 45% to 56% (USDHHS, 2008). We believe that the results from our study will further our understanding of dental care usage and needs among young adults with ID and without ID, identify areas for intervention, and help work toward the goal of increasing the proportion of young adults using dental care systems every year.

For a child with ID, the latest estimate for excess lifetime costs above costs incurred for a typically developing child is close to one million in 2003 U.S. dollars (Honeycutt et al., 2004). However, this might be an underestimate, because lifetime medical costs for individuals with ID have limited measures for quantifying dental care, and thus might result in omission of these services from current estimates (Honeycutt et al., 2004). Because periodic dental care thwarts progression of periodontal disease in young adults, particularly among those with disabilities (Yoshihara, Morinushi, Kinjyo, & Yamasaki, 2005), accessing care early in life can significantly reduce lifetime costs associated with ID (Glassman & Folse, 2005; Savage, Lee, Kotch, & Vann, 2004). With an aging cohort of children and young adults with ID facing other health problems stemming from untreated or poorly treated dental conditions, access and use of dental care at an early age should be an attainable priority (Hennequin, Faulks, & Roux, 2000).

In summary, our study identified a statistically significant disparity in dental care visits among young adults with and without ID. Young adults transitioning from pediatric to adult dental care face unique challenges regarding dental care. Changing living conditions, lack of dental insurance, and disappearance of community-based programs that cater to preventative care might force young adults to neglect dental care. These young adults should be identified, particularly those who do not have a high school education and who are not receiving vocational services, and information should be provided to their caregivers regarding resources for improving their dental care. Targeting dental services to young adults by increasing awareness and improving resources can help to reduce overall costs associated with delayed treatments, as well as restorative or emergency dental care. Finally, legislative policies that promote recommended dental care among young adults, particularly those with disabilities might help improve use among younger populations.