In “Drilled!” at the Palladium: Mario Gonzalez, Chris Loving and Bailee McQueen. All photos provided by Bill Leavengood. It was Bill Leavengood’s dental hygienist, of all people, who planted the seed for his newest play. “Hey,” she’d said as he climbed out of the chair, “you ought to set a musical in a dentist’s office.” […]