[1] Univ Bonn, Dept Orthodont, Sch Dent, D-53111 Bonn, Germany
[2] Univ Bonn, Dept Oral Technol, Sch Dent, D-53111 Bonn, Germany
[3] Univ Bonn, Clin Res Unit 208, D-53111 Bonn, Germany
[4] Univ Bonn, Ctr Dentomaxillofacial Med, Sect Expt Dentomaxillofacial Med, D-53111 Bonn, Germany