When Teresa Nolan Barensfeld turned 65 last year, she quickly decided on a private Medicare Advantage plan to cover her health expenses.

Barensfeld, a freelance editor from Chatham, New York, liked that it covered her medications, while her local hospitals and her primary care doctor were in the plan’s network. It also had a modest $31 monthly premium.

She said it was a bonus that the plan included dental, hearing and vision benefits, which traditional Medicare does not.

But Barensfeld, who works as a copy editor, missed some of the important fine print about her plan. It covers a maximum of $500 annually for care from out-of-network dentists, including her longtime provider. That means getting one crown or tending to a couple of cavities could leave her footing most of the bill. She was circumspect about the cap on dental coverage, saying, “I don’t expect that much for a $31 plan.”

Through television, social media, newspapers and mailings, tens of millions of Medicare beneficiaries are being inundated this month — as they are each autumn during the open enrollment period — by marketing from Medicare Advantage plans touting low costs and benefits not found with traditional Medicare. Dental, vision and hearing coverage are among the most advertised benefits.

Those services are also at the center of heated negotiations on Capitol Hill among Democrats as they seek to expand a number of social programs. Progressives, led by Sen. Bernie Sanders (I-Vt.), are pressing to add dental, vision and hearing benefits to traditional Medicare.

Despite the high-powered advertising of the Medicare Advantage plans pitched by the likes of celebrities Joe Namath and Jimmie Walker, beneficiaries still generally end up with significant out-of-pocket costs for many of these services, a recent study by KFF found. That’s partly because the private plans limit benefits. While people in traditional Medicare paid on average about $992 for dental care in 2018, those in Medicare Advantage plans paid $766, according to the study. For vision, people with traditional Medicare paid $242, compared with $194 for those covered by a Medicare Advantage plan.

“It stands to reason there would be lower out-of-pocket spending in Medicare Advantage than in traditional Medicare, but the differences are not as large as one might expect,” said Tricia Neuman, a senior vice president at KFF and executive director of its Medicare policy program.

More than 26 million people were enrolled in Medicare Advantage plans for this year — 42% of all Medicare beneficiaries. Enrollment in the private plans has doubled since 2012 and tripled since 2007. Unlike traditional Medicare, these private plans generally allow coverage through a limited network of doctors, hospitals and pharmacies.

Open enrollment for 2022 plans runs from Oct. 15 to Dec. 7, and some Advantage plans offer enticements such as hundreds of dollars’ worth of groceries, home-delivered meals or $1,000 in over-the-counter items such as adhesive bandages and aspirin.

But many seniors don’t realize there are restrictions on these benefits. They may cover extras only for enrollees with certain health conditions or have a narrow network of providers or annual dollar limits, often around $100 for vision or $1,300 for dental.

“All these extra benefits encourage people to sign up, but people don’t know what they have until they try to use it,” said Bonnie Burns, a training and policy specialist for California Health Advocates who helps Medicare beneficiaries evaluate their health plan options.

Seniors typically can choose from more than 30 Medicare Advantage plans sold by several insurers. The choice is so daunting that fewer than a third of seniors bother to shop and compare during the open enrollment window — even though costs and benefits change every year.

And for those who want to shop around, comparisons are not easy. The Medicare.gov website provides an overview of health plan costs and benefits and lets seniors compare plans’ premiums based on what medications the beneficiary uses. But it doesn’t offer a comparison of which doctors, dentists or hospitals are in the Medicare Advantage network or provide details about limits on dental, hearing and vision care. For that information, consumers must go to each insurer’s website and read through a summary of benefits that can be dozens of pages long.

Mary Beth Donahue, CEO of the Better Medicare Alliance, a research and trade group representing Medicare Advantage plans, sees things differently. “Medicare Advantage’s flexible benefit design means that beneficiaries can choose a plan tailored to their needs — whether that means more robust coverage, or more basic coverage, potentially for a lower cost,” she said.

Casey Schwarz, senior counsel for education and federal policy at the Medicare Rights Center in New York, an advocacy group for seniors, said the extra benefits offered by plans have increased confusion among beneficiaries. Those benefits come at a price.

“There is almost always a trade-off such as narrower provider networks, tighter drug formulary or restrictions in other areas,” she said.

Jenny Chumbley Hogue, an insurance broker near Dallas and an analyst at medicareresources.org, which helps seniors navigate the program, said marketing misleads some of her clients. “They see a TV ad that says they can get everything for free when they may not qualify for those benefits,” she said. “It’s hard to know if they are misinformed or not reading the fine print.”

She added that consumers should choose a plan based on whether their doctor is in that network or their drugs are covered at the lowest cost. For example, while most plans offer a hearing aid benefit, it’s usually only for a certain type of aid from a single company, Chumbley Hogue said.

“The devil is in the details, particularly when it comes to dental,” she said. “The coverage is not typically what they are used to coming from an employer plan.”

Medicare Advantage dental benefits are becoming more robust, though. Nearly 90% of the private plans offer dental benefits at no extra cost and most offer coverage for treatment as well as cleanings and checkups, according to a report by the consulting firm Milliman. The percentage of plans offering preventive and comprehensive dental has jumped to 71% this year from 48% in 2019.

Plans also are increasing benefits so they meet Medicare’s requirement to spend at least 85% of enrollees’ premium dollars on health services, Neuman said. Plans that don’t reach that threshold can face sanctions, including not being allowed to enroll new members.

While some consumers may find the dental benefit alluring, not everyone uses the coverage. The Medicare plan may not cover their existing dentist, so they continue to pay out-of-pocket, she said.

Medicare Advantage beneficiaries use their dental benefits less frequently than people with dental coverage through their employer, said Joanne Fontana, a principal with Milliman. “Not everyone buys a plan because it covers dental,” she said, “and it’s not top of mind or they [don’t] think to go the dentist every year.”