The association between financial hardship and medical care isn’t new. Even in wealthy countries such as the U.S., medical bills contribute to a large percentage of personal bankruptcies. Now, a new global study finds that dental care can also contribute to families falling into poverty and being left with fewer financial resources for basic necessities.

In a study published today in the journal PLOS ONE, researchers found that up to 7 percent of households surveyed in 41 low- and middle-income countries had experienced catastrophic dental care expenditures in the last month. To conduct the study, researchers analyzed data from more than 182,000 respondents ages 18 and older in 41 countries and who participated the World Health Organization’s World Health Survey. Spending on dental health care was defined as “catastrophic” if the expenditure was equal to or higher than 40 percent of the household capacity to pay for the care.

The study found that wealthier, urban and larger households as well as more economically developed countries had higher odds of experiencing catastrophic dental care expenditures, while in low- and middle-income countries, the use of dental care was more typically associated with the ability to pay than with a person’s oral health needs. Study authors Mohd Masood, Aubrey Sheiham and Eduardo Bernabe write:

Treating oral diseases is costly, even in high-income countries where 5–10% of public health spending is used for dental care. Although there is no equivalent data for low-income countries, it has been estimated that treating (tooth decay) in children would cost between $1,618 and $3,513 per 1,000 children of mixed ages from 6 to 18 years, an amount that exceeds the available resources for the provision of an essential public health care package for the children of most low-income countries. Those needing dental treatment face two important economic consequences: the high direct costs of the service (out-of-pocket expenditure) and the indirect loss of income and productivity to attend services.

Researchers found that the proportion of households experiencing catastrophic dental care expenditures in the prior four weeks ranged from 0.1 percent in Namibia and Lao to 6.8 percent in Ukraine. In a separate analysis that excluded households with no dental spending, the percentage of households whose expenditures on dental care in the prior four weeks was defined as “catastrophic” ranged from 2.8 percent in Swaziland to 35 percent in Ukraine.

In addition, households with three or more children faced lower odds of experiencing catastrophic dental care expenditures than those with no kids, while households with three or more adults faced higher odds of catastrophic dental care expenditures than single adult households. Overall, catastrophic dental care expenditures were more likely in urban areas than in rural areas. At the country-level, the odds of facing catastrophic dental care expenditures rose 1.17 times for every $1,000 increase in gross domestic product per capita.

While it seems somewhat backward that catastrophic expenditures were more likely in higher-income nations, the study authors explained that dental care in lower-income countries is primarily financed through out-of-pocket spending, while people in wealthier, more urban households are more likely to take advantage of high-cost, private dental care providers. As for the lower risk among households with children, the study noted that most developing countries offer publicly funded health services for children, which decreases the financial burden on families. The researchers added that stronger social norms around the appearance of a person’s teeth might also contribute to more dental care spending in higher-income countries.

The study authors concluded: “There is an opportunity for dental public health advocates and international dental organizations to incorporate dental care in current discussions about universal health coverage and its role in achieving equity in the use of health services.”

In a study published last month in the Journal of Dental Research, researchers estimated that untreated tooth decay, which can lead to infections, chronic pain and disease, affected more than 2.4 billion people globally in 2010, making it the most prevalent health condition in the world. In the U.S., tooth decay is the most prevalent chronic disease among children and adults, even though it’s totally preventable.

To download a full copy of the dental care expenditure study, visit PLOS ONE.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for more than a decade.