America's Great Dental Divide

How often you go to the dentist can predict not just income, but social class, political orientation, even what part of the country you live in

Image REUTERS/Phil Noble
REUTERS/Phil Noble

There's seemingly no end to the economic, political, and cultural divides that separate Americans: Republican vs. Democrat, religious vs. secular, beer vs. wine drinkers, Starbucks vs. Dunkin’ Donuts, NPR vs. the NRA, NASCAR vs. World Cup Soccer. But data released this month by the Gallup Organization shows a stark new axis of socioeconomic cleavage: those who regularly go to the dentist, and those who do not.

Derived from a large-scale database of some 177,000 interviews, conducted as part of the ongoing Gallup-Healthways Well-Being Index, the map below shows how the 50 U.S. states stack up in terms of the frequency of visits to the dentist. The variation across states is considerable. People in Massachusetts and Connecticut were much more likely to have visited the dentist over the course of the last 12 months than those in the South. Gallup notes that dentist office visits tend to track income level and health insurance coverage. The states whose residents are most likely to visit the dentist have some of the lowest uninsured rates in the nation.

With the steady statistical hand of my colleague Charlotta Mellander, I decided to take a closer look at this state-by-state pattern, comparing the Gallup-Healthways data on dentist visits to key economic, social, demographic, and political features. With the caveat that these are only associations and cannot be presumed to have a causal relationship, the strength of the correlations is astounding—among the highest we have seen in any analysis of this sort we have undertaken.

Income is key, as the Gallup-Healthways study surmised. People see a dentist more frequently in higher-income states. The correlation between the two is considerable (.66). But income is not the only factor to play a role. Using a statistical technique called partial correlation analysis, we can control for its effects and see how important other factors are. All the correlations we report below have income factored into the equation.

Dental visits closely track socioeconomic class. They are much higher in states where a higher percentage of the workforce is employed in knowledge, professional, and creative work. The creative class is significantly associated with dentist visits (.31). The same is true of the share of college graduates, a measure of the knowledge base and human capital in a state. The correlation between dental visits and college grads is even higher (.65). On the flip side, visits to the dentist are negatively associated with the working class share of a state’s workforce (-.28).

Income inequality in the U.S. has worsened over the past couple of decades, with the rich getting richer and the share of Americans in poverty increasing substantially. Income inequality also factors into oral health. Dental visits are fewer in states with higher levels of income inequality. Income inequality (measured as the Gini coefficient across states) is negatively associated with going to the dentist (-.63).

The combination of rising poverty, fewer jobs and the economic crisis means that many Americans are working longer hours to make ends meet. Oral health is negatively associated with working hours (-.74).

While some have argued that race is diminishing in importance, it remains a significant fault line in American life.  And so it is with oral health. Dental visits are positively associated with the percent of the population that is white (.3) and negatively associated with the share that is black  (-.6).

The Gallup study notes the connection between poor dental health and other health problems.

Poor oral care can lead to many potential negative health outcomes. When combined with other risk factors, poor oral health can be linked to heart disease, stroke, atherosclerosis, rheumatoid arthritis, and diabetes, among others. Maternal periodontal disease, too, has been linked to preterm births.

We find close associations between oral health and two key health factors: smoking and obesity. Visits to the dentist are negatively associated with both smoking (-.55) and obesity (-.6). Not surprisingly, more frequent dental visits are associated with higher levels of overall happiness and subjective well-being (with a correlation of .57).

Oral health also reflects the underlying divide between Red and Blue America. Oral health is positively associated with states that voted for Obama in 2008 (.38) and negatively associated with McCain states (-.42).

Access to dental care stands as a remarkably stark divide in American life, but it shouldn't come as a surprise. More than four in ten Americans pay their dental bills themselves, compared to just 10 percent of doctor’s visits, and the past decade or so has seen a vicious “oral cost spiral,” as June Thomas points out, with the costs of dental care far outpacing both the rate of inflation and overall medical cost increases. With incomes falling, unemployment rising, and poverty increasing, dental care has become a “luxury” that fewer and fewer Americans can afford—and this despite the high premium that we put on appearance. “We rarely think about our teeth, but without them many of us would be up a creek socially and economically,” writes Ylajali Hansen at Generation Bubble. “For many Americans, a tooth can make the difference between security and destitution. That’s right: lose a tooth in the United States and you lose your chance to live the dream. Poverty and emotional desolation follow soon upon the unfortunate loss.”

It’s getting so that your smile alone is enough to tell people not just how much money you make, but your social class, political orientation, and even what part of the country you live in. And for far too many Americans, there’s less and less to smile about.  

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