Yes, you can pay for dental and vision insurance from your HSA if you are 65 or older.
Section 223(d)(2)(C)(iv) states that anyone who has reached Medicare age (currently 65) can use HSA funds to pay for "any health insurance other than a medicare supplemental policy". See https://www.law.cornell.edu/uscode/text/26/223
While the instructions are somewhat vague ("other health care coverage"), the law authorizing HSAs in the first place (Section 223) is quite clear.