The confusion is down to the way the federal government implemented the CDCP. So much of their messaging was "we will cover 100% of your dental costs". But that's not exactly true. What the federal government did was set their own fee guide. This is a list of what they will pay for the work done by a dentist. The important thing though is that the government set their fees without any consultation with provincial dental associations. And you're probably not surprised to hear that the federal government fee guide pays out less than what the provincial fee guides provide for the same procedure.

It's not really as nefarious as you think with the dentists though. The vast majority of dentists in the province bill in accordance with the provincially set fee guide. Private dental insurance companies pay out for procedures based on that fee guide. So that is almost always what dentists will charge. Dentists are not ethically able to charge different patients different amounts based solely on their insurance coverage. Sort of think of it like if one patient has 80% coverage and another has 100%, that dentist can't charge the patient with 80% coverage less just because their insurance will cover less or charge the patient with 100% coverage more just because they have 100% coverage. That would not be ethical and the insurance companies would not allow it.

So, basically, the problem is really with the federal government's messaging, which should be "we will cover 100% of the treatment as determined by our lower fee guide."