Original Medicare enrollees have the option of adding a commercial stand-alone dental policy. For example, a Delta Dental P.P.O. plan offered in New York City carries a monthly premium of $48, with an annual deductible of $50 and an annual per-person payment limit of $1,500.

Many of the current Medicare for All proposals would add coverage of dental, vision and hearing care.

Someone called me claiming to be from Medicare and I gave out my Medicare number. Should I be concerned?

Medicare generally does not initiate calls to enrollees — with a couple of exceptions. Medicare health or drug plans can call current members. And customer service representatives from Medicare (1-800-MEDICARE) may call if you have left a message, or if a representative indicated that you would receive a return call.

Never give out your Medicare — or Social Security — number to anyone who calls you on the phone, sends email or makes a personal contact. Your personal information, including your Medicare number, should be shared only with health care providers, your insurers or trusted counseling services, such as the State Health Insurance Assistance Program.

“Any unexpected call from someone claiming to be from Medicare is a huge red flag, especially if you didn’t call first,” says Amy Nofziger, director of fraud victim support at AARP.

AARP’s fraud help line (877-908-3360) has noted a recent increase in phone schemes, usually aimed at persuading people to order equipment or services that are then billed to Medicare. “A big one lately has been DNA genetic testing kits,” Ms. Nofziger said. The Medicare program isn’t the only victim of the phony bills, she said. “Sometimes, Medicare will deny the claim and then the perpetrator mails a bill to the enrollee. You might get a bill for up to $10,000, which is pretty scary for people.”

If you suspect you’ve been victimized by fraud, alert Medicare that a scammer may have your identifying number so that your account can be flagged and monitored. And, keep a careful eye on the monthly explanation of benefits that Medicare sends, looking out for any suspicious charges.