There is a lot of really confusing information out there about access to Dental, Vision, and Hearing benefits with Medicare. Original Medicare does not provide coverage for Dental, Vision, or Hearing. The only exceptions to this rule is for a disease, disorder, or trauma / injury to a tooth or an eye, an example would be cataracts removal. Routine care for vision, dental, and hearing are not currently covered by Original Medicare.
There are discounts available on Dental care through some Medicare Supplement plans but it's just that...a discount...not dental insurance.
Most Medicare Advantage plans offer some sort of Dental coverage, it may be a discount or dental reimbursement coverage. You'll typically find that you'll need to see an "in-network" dentist, and your coverage could include bi-annual routine cleanings, x-ray, and some small amount of coverage for services the plans deem to be Comprehensive.
Medicare Advantage plans may offer some form of routine vision care. Typically an annual routine eye exam and possibly even an allowance towards your purchase of glasses. Original Medicare does cover care for diseases or disorders of the eye and a pair of glasses following cataracts removal surgery.
Hearing aids are also not covered by Original Medicare and there is usually no coverage with Medicare Supplements either. Some Medicare Advantage plans offer an allowance towards Hearing Aids and, if you find that you're in need of hearing aids, this can be really helpful.