October 2007

Symposium: Is it Time for a Universal Dental Scheme in Australia?

Inequality in oral health in Australia

John Spencer, University of Adelaide
Jane Harford, University of Adelaide

INTRODUCTION

An acceptable level of oral function and freedom from pain and discomfort is a reasonable aspiration for all people. This creates both an imperative for improved population prevention of more oral disease for all people as well as the better management of the consequences of disease for those who are currently suffering adverse impacts. Our ideals of social justice should be affronted by the numbers of people on low and middle incomes who are living with more untreated disease, experiencing more pain and greater dysfunction until their disease is treated, and not being appropriately ‘rehabilitated’ where treatment is finally received. Income related inequality in health care is not acceptable for other contiguous body parts like eyes, ears, sinuses or throats. Access to health care of these body parts is assisted by universal health insurance. Yet inequalities in dental care seem to have been accepted within the health care system. They should not be.

Oral disease can exacerbate underlying general disease.

‘You cannot be healthy without oral health’ (US Department of Health and Human Services 2000, p. 2). Oral health is important in its own right and because oral and general health are linked. Oral disease is associated with systemic disease. For a number of conditions oral disease is in the causal pathway. For instance, appalling oral health in older adults has been linked to aspiration pneumonia. For other systemic diseases, as varied as pre-term low birth weight babies and cardiovascular disease later life, evidence suggests associations with poor oral health that at least justify concern and further research. Oral disease can also exacerbate underlying general disease and complicate and frustrate its management. Indeed, this is the theoretical underpinning for ‘medically necessary dental treatment’ and the inclusion of dental care in management of chronic or complex medical problems (Rutkauskas 2000). A ready example is diabetes, where glycaemic control can be made more difficult by advanced periodontal disease. Unfortunately some people die of oral disease, for example septicaemias and oral cancer, and poor oral health may contribute to death and disability from many other general causes.

Dental care offers an opportunity for a point of intervention that can reduce the risk of oral and general health problems. Oral and general diseases not infrequently share common risk factors (Sheiham & Watt 2000). Smoking illustrates this common risk for multiple diseases well. Comprehensive dental care should include an assessment of smoking status and assistance for those smokers who may wish to quit. But this does not occur when a person makes an emergency visit to the dentist because they are in pain, because band-aid treatment of the complaint they present with is the only care on offer. The opportunity to integrate dental care into the wider health care system, to gain synergies and to reinforce preventive interventions is missed for many when dental care is not better supported in the health system.

To contribute to improvement of oral health policy in Australia we need to explore what we do know about oral health inequality and the evidence for ways in which inequality can be reduced.

INEQUALITIES IN ORAL HEALTH

Inequality in oral health in Australia has been extensively documented over the last 25 years. While the existence of inequalities has been accepted, their fundamental character has been less well understood. This has led to a misinterpretation of the information on inequalities and a failure to act on their causes.

One reason has been the lack of good information in the form of large-scale population oral epidemiological studies in Australia. One consequence of this lack has been concentration on smaller ad hoc oral health studies, generally focused on sub-groups of the population. These studies have documented poor oral health outcomes, but such outcomes have been interpreted as isolated pockets of poor oral health among a minority of people who make up disadvantaged sub-groups in the population. This diminishes the apparent extent of the inequalities in oral health and encourages a policy response directed only at a small minority of the population.

There is little variation in the underlying lifetime experience of dental decay.

In the absence of large oral epidemiological studies, researchers and policy-makers have relied on social surveys. These are very appropriate vehicles for self-reported indicators of oral health, but they do not shed a strong light on underlying experience of disease. Inequalities in aspects like reported symptom experience or oral health-related quality of life are assumed to reflect experience of disease. This provides solace for an individualistic and predominantly behavioural explanation of inequalities. Meanwhile, the more important challenges of understanding how structural features of the dental care system bring about apparent inequalities in oral health outcomes and formulating policy that addresses those underlying structural features can be avoided.

Although large scale studies are not available, we can learn about oral health inequalities from a small scale, but rigorous oral epidemiological study conducted in 2005 in metropolitan Adelaide. The study involved a representative population sample with a narrow age range, 45–54 years old (Brennan, Spencer & Roberts-Thomson 2007). Narrowing the age range is useful as it diminishes age as a confounder in the relationship between social position and oral health. Social position has been characterised by household income divided into approximate quartiles and oral health has been measured by clinical indicators of caries experience, focused around the numbers of teeth present and how many have untreated decay (D), are missing because of pathology (M) or have been restored (F) and the sum of these indicators, the Decayed, Missing and Filled Teeth Index (DMFT), derived from dental examinations.

Having an inadequate dentition, defined as less than 21 teeth, is a ready clinical indicator of oral dysfunction. Table 1 shows the percentage of middle-aged adults with an inadequate dentition was seven times higher in the lowest (12.4%) than the highest (1.7%) income quartile. There was clearly a substantial inequality in this oral health outcome. However, did this reflect an inequality in underlying disease experience?

People come to have inadequate dentition because some or all of their teeth have been extracted. The vast majority of teeth lost by people aged 45–54 are extracted because of dental decay (Chauncey, Glass & Alman 1989). Table 1 shows that there is only modest variation across household income quartiles of cumulative past and present experience of decay. The DMFT Index varied from 17.14 to 15.35 teeth between the lowest and highest income quartile—in other words, it was only 1.12 times greater in the lowest income quartile than in the highest. Therefore, there was little variation in the underlying lifetime experience of dental decay. However, comparing the individual components of the DMFT Index shows more substantial inequality. Adults in the lowest income quartile had eight times the mean number of untreated decayed teeth (0.80 teeth) than those in the highest income quartile (0.10 teeth). The number of missing teeth was a little over one and a half times greater among adults in the lowest household income quartile (6.57 teeth) than those in the highest income quartile (4.02 teeth). The number of filled teeth was fewer among adults in the lowest income quartile (9.77 teeth) than all other quartiles (range 11.48–11.23 teeth).

Inequality is markedly reduced among adults who visit a dentist more frequently.

These data establish that there was only modest inequality in the underlying lifetime dental decay experience. However, the outcome of the management of dental disease was more varied. Lower income groups were more likely to have had no treatment for their dental disease, and more likely to have had a diseased tooth extracted (the M teeth component) rather than filled (the F teeth component). Thus, there are much more substantial inequalities in oral health outcomes than underlying oral disease experience.

This interpretation of oral health inequalities is consistent with other observations. For instance, Davis (1981) established that edentulism (having no natural teeth) was unrelated to underlying oral disease experience. Instead, edentulism and part edentulism (or tooth loss) were related to patterns of treatment. The observation that inequalities in oral health are marked for oral health outcomes, but less so for underlying disease experience is also consistent with inequality in the percentage of the adult population with self-reported edentulousness (no natural teeth), self-rated ‘average’, ‘poor’ or ‘very poor’ oral health, symptom experience, and oral health-related quality of life (Spencer 2004). The individual components of the DMFT Index and these self-reported indicators of oral health are sensitive to inequality in the management of the underlying experience of oral disease.

ORAL HEALTH OUTCOMES BY ACCESS TO DENTAL CARE

How oral disease is managed is linked to access to dental care, where access is the availability, obtainability and comprehensiveness of care (Lewis, Fein & Mechanic 1976). Management of disease varies through lack of providers, delay in being seen, the stage of disease at presentation, and rationing of specific treatment when people with disease finally receive dental care.

Does favourable access to care attenuate the marked inequalities in oral health outcomes? Table 2 presents the two clinical indicators with the greatest inequality by income, an inadequate dentition (less than 21 teeth) and untreated decayed (D) teeth by income and usual frequency of visiting (infrequent versus frequent, that is, at least once per year).

Table 2 shows that among adults who visit a dentist infrequently, inequality between lowest and highest income quartile was around eightfold for both inadequate dentition (18.7 per cent compared to 2.3 per cent) and for untreated decayed teeth (1.23 teeth on average, compared to 0.11). The inequality was markedly reduced among adults who visit a dentist more frequently. An income gradient still existed, but that gradient was only about twofold between lowest and highest income quartiles. Adults in the lowest income quartile who visit more frequently had oral health outcomes more similar to adults from the highest income quartile who visit infrequently, than to low income adults who visit a dentist infrequently. This study compares only one proxy measure of access to dental care: frequency of visiting. If measures of reason for visiting and comprehensiveness of care were also taken into account, the income gradient in these oral health outcomes may cease to exist.

INEQUALITIES IN ACCESS TO DENTAL CARE

Clearly, access to dental care is the underlying reason for variation in management of oral disease experience. What evidence is there on inequalities to access to care? Again, the recent oral epidemiological study in Adelaide can illustrate inequalities in the frequency of visiting (last twelve months or not), the reason for visiting (check-up versus problem) and comprehensiveness of services received (Table 3).

Inequality in access has a cumulative impact on oral health outcomes.

Table 3 shows that adults in the highest income quartile were more likely to have visited a dentist in the last twelve months than those in the lowest income quartile (76.9 per cent compared to 55.1 per cent) and were nearly twice as likely to have visited for a check-up (55.3 compared to 31.5 per cent). In addition to barriers to visiting a dentist, there were differences in services received at a dental visit that show the different management of the disease experienced. Those in the highest income quartile were more likely to receive a scaling of their teeth (60.7 per cent compared to 35.6 per cent) and less likely to receive an extraction (3.7 per cent compared to 13.5 per cent) than those in the lowest income quartile.

These inequalities are not as dramatic as inequalities in some oral health outcomes. However, variation in dental care exists not just across the recent past for these adults, but over long stretches of the life course. Thus, inequality in access has a cumulative impact on oral health outcomes. These inequalities in access to dental care are not dramatic, but they are most likely larger than those for other areas of health care. About two- to three-fold more people report foregoing dental care than medical care, having a prescription filled or a test done, and follow-up care due to cost (Blendon, Schoen, DesRoches et al. 2002).

REDUCING INEQUALITIES IN ACCESS TO DENTAL CARE

Little of the documented inequality in oral health outcomes arises from social patterning of knowledge or attitudes about oral health or systematic variation in preventive dental health behaviours like tooth-brushing (Sanders, Slade & Spencer 2006). Instead inequality arises from the cumulative effect, across the life course, of differences in the social context in which people live their lives and their access to dental care. Thus, patterns of visiting and the comprehensiveness of services received are amenable to policies that work to improve access to dental care across the population. Policies that address financial barriers to timely care can affect both the frequency of visits and their purpose. More frequent, preventative-oriented treatment sets the groundwork for higher rates of preventive care and lower rates of extraction.

In the context of Australian oral health policy an important question here is: does insurance make any difference? Insurance coverage information is not available for the Adelaide study discussed above, but insurance coverage information was collected in the National Dental Telephone Interview Survey (NDTIS) conducted in 2004–2006. NDTIS is a representative telephone interview survey of households in all Australian states and territories in which socio-demographic, self-reported oral health and dental visiting information are recorded. Results reported here have been weighted to account for differing sampling probabilities due to the sampling design and further weighted by age and sex characteristics for each sampling stratum across states and territories. Data for people aged 45–54 year-olds from NDTIS can be used to examine the impact of dental insurance on these patterns of visiting and services actually received to complement the earlier data from Adelaide adults aged 45–54 years old. Some difference exists between the two studies in the exact nature of the dental visiting variables and further difference in estimates arises from the metropolitan Adelaide versus all of Australia sampling frame.

Adults from low income have the poorest oral health outcomes.

Table 4 shows the percentage of people who visited a dentist in the last twelve months and whether they visited for a check up within the last two years by income quartiles and dental insurance status. There was a modest difference in the overall percentage of adults in each income quartile who made a dental visit in the last twelve months, but only among those not insured. Among those with insurance, there was a slight gradient with income, but this was in the opposite direction: holding dental insurance was an increasingly important factor in making a recent visit as income decreased. Both being insured and having a higher income substantially increased the likelihood of usually visiting for a check-up. Holding dental insurance at lower income ranges was associated with visiting patterns similar to those of people in the highest income quartile who were not insured. Finally, there is an affordability gap across income quartiles between those who have dental insurance and those who do not. In all income quartiles a substantially lower percentage of the insured than those not insured reported that they had avoided or delayed visiting a dentist due to cost. This gap was greatest for those adults in the lowest income quartile.

Overall, then, these data show that holding insurance was associated with more positive visiting patterns and with fewer extractions and more preventive care being received in the last twelve months. Table 5 indicates that both lower incomes and lack of insurance are associated with having a tooth extracted. Once again, being insured in the lowest income quartile was associated with extraction rates closer to those for adults in the highest income quartile, both insured and not insured. In addition, at all income levels, being insured is associated with a higher prevalence of having a tooth scaling and having insurance at lower income quartiles was associated with similar patterns of care to people in higher income quartiles.

OPTIONS FOR REDUCING ORAL HEALTH INEQUALITIES

What are our options for narrowing the inequality gap in oral health? Most attention to the inequalities in oral health outcomes and access to dental has focused on specific disadvantaged groups in the Australian community. Certainly, adults from households in the lowest income quartile have the poorest oral health outcomes and least favourable access to dental care. However, the analysis presented above establishes a gradient in oral health outcomes and access that runs considerably higher up the income distribution. Therefore, it seems unlikely that solutions that target only those on low incomes will be a sufficient response, and policies that extend to groups with incomes well above those of people with government concession cards are required. Universal insurance would satisfy this requirement, as would a policy of subsidising private dental insurance into the middle-income quartiles with a tapering off in the level of subsidy at higher incomes.

During the last 20 years there has been some public interest in, and discussion about, including dental services within Medicare. When this question has been considered before, two issues have tended to dominate: cost and willingness of the dental profession to be involved. Two other issues—the relatively small cost to individuals and the chronic, predictable nature of dental services—have been canvassed by the two commonwealth government committees that have examined the question of inclusion of dental care in Medicare (Medicare Benefits Review Committee 1986; Senate Select Committee on Medicare 2005) The first two issues clearly need to be worked through at a political level if agreement upon them is to be reached. It is, however, worth revisiting the question of the suitability of dental care for insurance.

There is currently a shortage of dentists in Australia.

The argument that dental care is not a good candidate for insurance because it is neither episodic nor unpredictable should be reconsidered in light of two important points. First, treatment for many chronic conditions is insured for under both Medicare and private health insurance, so this should not be a reason for excluding dental care. Second, while the incidence of most common oral diseases can be predicted at a population level, it is very difficult to predict at an individual level, even for dental professionals. Third, public dental services in Australia fail to provide good quality care to all who are eligible for them. This is largely because they are not funded to the level that would give access to all eligible adults. Yet access to general health care is not so manifestly unequally distributed as access to good dental care. One reason for this may be that all Australians use these services and that creates pressure for a minimum standard across the population. An extended insurance scheme either within Medicare or through publicly subsidised private insurance may assist in improving access across the population.

Expenditure on dental services was reported to be $4.7 billion in 2004–2005 (Australian Institute of Health and Welfare 2006). This serves as a ready reckoner for the potential cost of including dental services in Medicare. However, it is likely to be a low estimate because the percentage of the adult population visiting dentists and the average number of visits to a dentist would increase if price considerations were largely removed from dental care. Whatever the actual estimate, it is most likely beyond what any future government will be willing to fund. It may also be beyond what the dental profession is able to supply in dental care. There is currently a shortage of dentists in Australia. Although there has been some response in recruitment of domestic and overseas trained dentists, supply constraints will cap what dental care can effectively be demanded (Spencer, Teusner, Carter & Brennan 2003). The organised dental profession also continues to argue against the inclusion of dentistry in any universal health insurance scheme (Matthews 2007). Such professional concern may have its base in evidence that universal coverage can act as a price control system within health care delivery (Altman & Jackson 1991; Leeder & Boxall 2005).

Both cost and professional opposition to involvement in any universal health insurance scheme lend support to a more measured approach. One more measured approach within universal health insurance would be to limit the scope of services covered to basic dental care. This would include a periodic dental check-up, diagnostic and preventive services, and a conservative range of restorative and periodontic (gum) treatments. The basic dental care package could follow the lead of the private dental insurers who frequently apply different eligibility criteria to different levels of dental treatment. This approach might still be very costly unless such dental care is only supported every two or three years. A variant of this restriction would be a limitation on eligibility, for instance to only young and/or old adults.

Any private dental insurance approach will still leave some adults facing crises in the affordability of dental care.

Alternatively, given the nature of the inequality in access to dental care, a more limited objective might be to subsidise private dental health insurance coverage among the lower and middle income quartiles to approximate the level evident in the highest income quartile. The percentage of adults covered by private dental insurance varies from less than 20 per cent among low income households to over 70 per cent in high income households (Spencer 2004). Little is understood why people on low incomes particularly do take out private health insurance. Generally, people cite security, choice, and a shorter wait for care as the main reasons they take out health insurance. People in lower income households said state the main reason they do not have health insurance is that it is too expensive or that they can not afford it. Thus, it seems that perceived cost is an important barrier to taking out health insurance for people on lower incomes (Australian Bureau of Statistics 2003). However there is no guidance on what level of coverage could be achieved among lower and middle income households through a greater subsidy than the 30 per cent rebate currently provided. Experience with the rebate for private health insurance indicated that the rebate might need to be a sizeable proportion of gross premium costs, but any such rebate would be applied to a markedly lower gross premium for private dental insurance only. Uncertainty about actual level of subsidy required for a wide community response in taking up private dental insurance indicates that policy would need to be fine-tuned over time to achieve its desired outcome.

To avoid the inequity of the current subsidy to private dental insurance, the rebate might be considerably higher than the existing 30 per cent for the lowest income quartile and reduce to the existing 30 per cent for the highest income quartile (Harford & Spencer 2004). This might be more palatable than removing the existing 30 per cent rebate from among high income households. A sliding scale of subsidy would be following the Australian government’s approach to other areas of social security such as relief for childcare fees and for family payments. The opportunity would also exist to legislate for ‘managed competition’ between health insurers in their plans for dental services. Dental services would provide a test area for such a policy in the Australian health area (Scotton 1998). It would be essential for inclusion/exclusion criteria for frequency and scope of services to be regulated and for consideration to be given to the gap between dental fees and insurance rebates. However, any private dental insurance approach will still leave some adults facing crises in the affordability of dental care.

Clearly there are policy options for responding to the inequality in oral health, not just among the lowest income quartile, but well up into middle-income households. Such policies may be financially more sustainable and receive dental profession support. Importantly, they could assist in reducing the inequalities in oral health outcomes among Australian adults.

ACKNOWLEDGMENT

We would like to acknowledge the two data collections from which data were drawn for this paper: the Impact of Declining Tooth Loss on Demand for Dental Care (Chief Investigators Brennan and Spencer) supported by National Health and Medical Research Council (NHMRC); and, the National Dental Telephone Interview Survey 2004-06, which was part of the National Survey of Adult Oral Health (Chief Investigators Slade and Spencer) which was supported by Australian Institute of Health and Welfare, the federal Department of Health and Ageing, the NHMRC, state/territory dental services, Colgate Oral Care, the Australian Dental Association and the US Centres for Disease Control and Prevention. Jane Harford is supported by an NHMRC Capacity Building Grant.

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John Spencer is Professor of Social and Preventive Dentistry and Co-Director of the Australian Research Centre for Population Oral Health at The University of Adelaide. His research background is in oral epidemiology and dental health services.

Jane Harford is a Research Fellow at the Australian Research Centre for Population Oral Health at The University of Adelaide. Her background is in public health, health policy and health economics. Her research interests include strengthening a public health/primary care approach to oral health and the impact of funding arrangements on oral health service delivery and status, and access to oral care.

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Australian Review of Public Affairs
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