Dwayne “The Rock” Johnson, the former pro wrestler-turned actor, started out as The Scorpion King. Now, he’s going to be transformed into — are you ready? — The Tooth Fairy. Johnson, who showed his softer side in “The Game Plan,” will play “an ordinary man who’s brought in to try to save the tooth fairy kingdom” in the 20th Century Fox comedy that will be directed by Michael Lembeck (“The Santa Clause”).