A lack of dental care for low-income Americans has long put stress on hospital emergency rooms, a new study has found, bring hundreds of thousands of patients in to ERs for minor dental problems.

The study, published this week in Health Affairs, found that in 2010, somewhere around 2 percent of all ER visits was dedicated to avoidable these patients, posing questions about how best to deliver dental care to poor people.

Authors of the study argue, however, that an expansion of dental care under Medicaid alone won't fix the problem. Patients relying on the federal program would still face limited access to dentists who are willing to take them.

The study looked at ER visits for 29 states, focusing specifically on non-traumatic dental care, such as cavities, tooth pain and gingivitis. The researchers found that areas experiencing an expansion of Medicaid dental coverage — especially urban areas — were not associated with fewer ER visits.

At the same time, rural counties that had plenty of dental providers did see a drop ER visits when coverage expanded, suggesting that the problem fundamentally lies in being able to find care.

"Just because they have the coverage doesn’t mean they have they access," said Maria Raven, an author of the study and a professor at the University of California-San Francisco. "If they don't have access via dentists that accept Medicaid, it doesn't matter."

It's well known that it Medicaid patients have a tough time finding dentists who will take them. The rate of dentists who accept the public aid patients fall to as low as 20 percent in New York, 15 percent in Florida and 11 percent in Missouri.

This is a problem because people who can't find a dentist will often put off getting care until their problem becomes a much larger (and more painful) health threat, and that gums up the entire emergency system. One study found that between 2001 and 2008, visits for minor dental conditions rose by 41 percent, while visits for all other conditions rose by only 13 percent during the same time period.

Federal law does not specifically mandate that dental care be given to adults on Medicaid. States have the option to include it as a benefit under the program, but not all do. The Affordable Care Act did, however, expand Medicaid overall, and as a result, around 8.3 million adults gained access to dental care in 2014, according to the American Dental Association.

Some states have also taken the steps to further expanded dental coverage for some Medicaid patients. Last year, Colorado introduced limited adult coverage for the first time, and California, Illinois, Massachusetts and South Carolina revived their benefits after cutting them in 2007. Indiana expanded its benefits this year, and Virginia added a benefit for pregnant women as well.

Still, as of January 2013, about 45 million Americans were living in regions with shortages of dental care providers, especially in rural and urban areas. What's worse, the amount of dentists is expected to decrease in the coming years as many are approaching retirement.

Authors of the study stress that the dental care ought to be treated as preventive care to avoid costly infections and extractions down the road. They did offer suggestions on how to reduce emergency room visits.

Dental clinics could create their own emergency departments and expand dental coverage that is less expensive. Options include experimenting with telehealth and increasing the number of mid-level dental providers, like hygienists. The government could also offer incentives for providers to refer patients to preventive care, similar to color and cervical cancer screenings.

"There are ways to build the dental services within Medicaid," said Katie Fingar, lead author of the study and a research leader at Truven Health Analytics. "That's a good option because the alternative clearly is not working."

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