"You don’t have to brush your teeth – just the ones you want to keep. -mom."
Just put up this note on the girls bathroom mirror. Maybe this will work? Why does getting the kids to brush their teeth seem like the work of Sisyphus? A figure of Greek mythology who was condemned to repeat forever the same meaningless task of pushing a boulder up a mountain, only to see it roll down again. It´s like the never fucking ending story..