"People with lower income end up with eight fewer teeth than the rich," The Independent reports.
The headline is prompted by a new study based on a 2009 national dental health survey of adults over the age of 21 in England. It found strong links between socioeconomic status (how well off a person is) and oral health.
The most extreme result was that the poorest fifth of elderly people had up to eight fewer teeth than the wealthiest fifth.
The finding that those who are worst off in society have poorer oral health than the wealthiest may not surprise many, and may well correlate with poorer health in general.
However, the study provides food for thought on whether the extent of the difference is acceptable or preventable.
The study's authors argue the routes of these inequalities require action "addressing risks, beliefs, behaviours, and the living environment", and that these factors may be just as important as affordable access to professional dental treatment.
Read more advice about dental health and how to mind those gaps.
Where did the story come from?
The study was carried out by researchers based at the University of Newcastle and the University of London, and was funded by the UK Economic and Social Research Council as part of the Secondary Data Analysis Initiative.
It was published in the peer-reviewed Journal of Dental Research.
The report opens with a quote from Chilean poet Pablo Neruda: "Rise with me against the organisation of misery". This quote highlights the authors' conclusion that the differences they have found are avoidable and are a product of the way our society is organised.
The media generally reported the story accurately, with many carrying a similar quote from the lead study author, who stated that, "It's probably not a big surprise that poorer people have worse dental health than the richest, but the surprise is just how big the differences can be and how it affects people."
Most of the headlines led with the figure that the poorest elderly people had up to eight fewer teeth than the richest. This result was not reported in the main results section of the publication, but was only mentioned in the discussion section, as this finding was not adjusted for confounders. Nonetheless, this does not diminish its significance in the wider context.
What kind of research was this?
This was a secondary analysis of a pre-existing dataset originating from a 2009 national dental health survey in England.
Oral health inequalities associated with socioeconomic status are widely observed, the research team says, but may depend on the way both oral health and socioeconomic status is measured.
The aim of this study was to investigate inequalities using diverse indicators of oral health and four socioeconomic determinants for age and cohort.
Using a pre-existing dataset is a relatively quick and simple approach to investigate the link between socioeconomic status and oral health.
The main limitation in using existing datasets, however, is often they do not collect all the data required for analysis.
This is because the original survey and data collection would have been designed for a specific purpose, which may be different from the purpose of the secondary analysis.
What did the research involve?
Researchers used existing data collected from a 2009 UK adult dental health survey to investigate how socioeconomic status was linked to oral health for adults.
This survey was based on a nationally representative sample of 11,380 individuals (among which 6,469 adults had an oral examination) providing information on individual dental health and socioeconomic status. The team restricted data analysis to adults over the age of 21.
The researchers wanted to see whether using different measures of socioeconomic status and oral health made a difference to how they were related, so they used multiple measures of each.
Oral health measures included:
- the presence of tooth decay
- the existence of teeth that couldn't be restored because of decay
- the number of decayed, missing and filled teeth
- the existence of any periodontal pocket (where the gums pull away from the teeth, creating a pocket) of 6mm or more
- the number of natural teeth
- having three or more unfilled upper spaces (to capture how the teeth might look)
- a composite measure of excellent oral health (21 or more teeth, 18 of which are "sound", with no decay or pockets greater than 4mm)
Socioeconomic measures included:
- index of multiple deprivation occupational social class
The analysis looked for links between each of the four measures of socioeconomic status and the seven measures of oral health.
The analysis took account of multiple confounders, including:
- marital status
- region of residence
- longstanding illness
- self-assessed health
What were the basic results?
The team consistently found people with lower incomes, lower occupational class, higher deprivation, or low educational attainment had the worst oral health outcomes. However, the size and significance of these inequalities depends on the clinical outcome used.
The two simple tooth decay measures – presence of tooth decay and the existence of more than one tooth that could not be restored as a result of decay – were still strongly associated with income after adjustment for confounders.
By contrast, the presence of any teeth with pockets of 6mm or more (severe periodontal disease), having unfilled upper spaces (untreated aesthetic impairment), and not having excellent overall oral health were weakly associated with income.
The number of teeth showed little or no income gradient in the young. By contrast, in older adults, those in the poorest fifth of income lost many more teeth than those in the top fifth, and the gradient was strong.
After adjustment for confounders, those in the poorest fifth had on average 4.5 fewer teeth than the richest fifth (95% confidence interval [CI], 2.2 to 6.8) but there was no difference in younger groups.
For periodontal disease, income inequalities were mediated by other socioeconomic variables and smoking, while for anterior spaces the relationships were age dependent and complex.
How did the researchers interpret the results?
The authors concluded that, "Oral health inequalities manifest in different ways in different age groups, representing age and cohort effects. Income sometimes has an independent relationship, but education and area of residence are also contributory.
"Appropriate choices of measures in relation to age are fundamental if we are to understand and address [oral health] inequalities."
In their discussion of the results, the researchers also added that, "In the oldest group, a huge difference between richest and poorest (based on current income) has opened up, and the unadjusted marginal difference was nearly eight teeth." This is the figure that made most of the media headlines.
This study provides a sharp look at the link between socioeconomic status and oral health. The finding that those worse off in society have poorer oral health is no surprise, and may well correlate with poorer health in general.
But what needs to be considered now is whether the extent of the difference is preventable. The most extreme result was that the poorest fifth of elderly people had up to eight fewer teeth than the wealthiest fifth.
On a more academic note, the study shows you can get slightly different results and patterns depending on which precise measure of socioeconomic status and oral health you choose – something future studies can learn from.
These findings are likely to represent a broadly accurate picture of the state of oral health in the UK and how it is related to various measures of income inequality.
But one drawback was that only four measures of socioeconomic status were tested. There are many more that are routinely used in other types of research, but the team were limited to using the information already collected as part of the original dental health survey.
The data suggests the links between different socioeconomic factors and oral health are complex. The authors themselves highlighted some wider determinants of health that may be at play, meaning a focus on treatment may not be the best approach to tackle the variation.
They remarked that, "There are many possible paths between socioeconomic position and oral health inequality that require further unpicking. However, while increasing resources for treatment services may provide benefits, the analysis here suggests that it will not resolve inequalities.
"Upstream action addressing risks, beliefs, behaviours, and the living environment are probably as important as affordable access to professional treatment."
This follows the sentiment of the Marmot Review "Fair Society, Healthy Lives", which dominates the wider public health agenda of tackling avoidable differences in health using an "upstream" approach.
An upstream approach is when rather than trying to change people's individual behaviours (such as encouraging tooth brushing), you instead change higher environment and social forces (such as adding fluoride to the water supply), which leads to beneficial effects flowing "downstream".