What your Mom gets with her Medicare Advantage plan is a start, and really not designed to cover all contingencies. I have looked at private dental insurance (in WA state), and as others have said, it just generally isn't worth much. Most policies here have a $1,000 limit on cost of care.
If she thinks she will have dental issues (fillings, tooth extraction, etc), then dental insurance will probably pay for HALF the costs (without factoring in the cost of premiums.
If she feels she will need just general check-ups and cleanings, she'll get about $100 in savings annually with dental insurance. That is: the value of what the insurance company pays will exceed her premiums, deductibles, and cost sharing by $100. If she has savings, IMHO, it is just better to fund the cost of care above what the MA plan pays for.
- Rita