From the author/illustrator of The Scrambled States of America, here is a fun-filled introduction to teeth. "Before the principal's announcements, will you all please stand and recite our pledge: 'I pledge allegiance to this mouth and to the dentist who takes care of us. And to the gums on which we stand, strong and healthy, with toothbrushes and toothpaste for all.'" It's time for tooth school…