This is not the answer that you want to hear and it may not be popular, but I have never found pet insurance that was a good deal for any routine type treatment. It seems to me that it is really only beneficial in case of an accident or sudden illness. When you add up the premiums and compare that to the limit that they will pay out in a year and the deductibles, exclusions, etc. it seems break even at best. With three dogs, I have looked at insurance several time, compared quotes, coverage, etc.
I think you would be better off to put money aside each month to pay for routine care and in the meantime call around for quotes on teeth cleaning. Let the vets know you are comparing prices.
Maybe someone else has had a better experience. That is just my opinion.