You're opening a can of worms here! There is no consistency and you can thank the ADA (who need to get off their dead asses) for that. The insurance companies, no doubt, also play a role here. They have to be willing to reimburse for the procedure and since this is more medical than dental it falls into a crack.

It ranges the gamut from responsible dentists, like Jerry, who voluntarily ponied up a lot of his personal fortune for the latest detection equipment to hygenists doing a cursory "exam" (like mine did), missing a 6x3cm tumor that was so large it was displacing my uvula (if they do any exam at ALL). My dentist doen't even have brush biopsy equipment but does note every anomoly (now) and routinely refers me to my H&N surgeon (which sees me regularly anyway). Some of these so called screening exams are so poor you might be better off with a Ouija board.

Until I am convinced that until there is an early detection STANDARD exam (like the Mammography Quality Assurance Act) I recommend seeing an ENT or H&N surgeon WITH H&N cancer experience. If you are a tobacco user or have other risk factors for oral cancer, pay out of your pocket for the ENT. It might be the smartest 75 bucks you ever spent. Get regular exams.

The excisional or "snip" biopsy is the gold standard. FNA biopsies can miss sometimes. I haven't seen data on the false positive rate for brush biopsies so if someone has more info please add it here.

It might take malpractice lawsuits to get their attention.

In all fairness however, many dentists may only see a few H&N patients in the entire course of their career.