Medicare Advantage plans generally have some basic dental coverage. Annual exam etc.
There’s an outfit called DentalPlans.com that gets you discounts if you select their network dentist.
Default approach: if anything serious arises, Los Algodones just across the Mexican border.
Aetna’s 2023 Medicare PPO plan premium is $87/month in California, free in many other states. The dental allowance is increasing from $750 in 2022 to $1250 in 2023. That’s enough for all your basic preventative plus enough left for a crown or some other major procedure.