I could write a book (or at least a good chapter) on this subject, but I can
give you the short version in one word... "none".  Your best insurance is
prevention and in having an honest, straightforward professional
relationship with a good dentist..

First; dental "plans" are not insurance!  For your money you get a list of
dentists who promise to pretend to give you a discount.  The dentists
typically get no money from these "plans", so they must somehow figure out
how to make money from you, the patient.  They have many ways of doing that
(honest and not-so-honest).  It is unlikely that you will beat the system.

Dental insurance companies make money by (on average) charging more in
premiums than they pay out in benefits.  In general, the benefits are
miserable unless the premiums are very high.  If you need dental work today
and you are thinking of buying insurance to pay for it, then forget it.  No
insurance company is going to pay for an existing condition.  Again, it is
unlikely that you will beat the system.

For decades I worked for the same company who included dental insurance as
part of my benefit package.  After trying various dentists on the provider
list, I finally figured out that it was cheaper and better to simply ignore
the insurance and go with a known-good dentist as a private patient.  I pay
for 6-month cleanings & exams.  Because the dentist gets to set a fair price
for his services, the dentist has no particular incentive to overtreat or
play any other games to make a living.  Since I have been doing that, my
annual dental expense has actually been far less than in the years I was
trying to use the dental insurance.

Vaughn