1. a Research Fellow, Department of Orthodontics, University of Rome Tor Vergata, Rome, Italy
2. b Assistant Professor, Department of Orthodontics, University of Florence; Thomas M. Graber Visiting Scholar, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, Mich
3. c Professor and Head, Department of Orthodontics, University of Rome Tor Vergata, Rome, Italy