[1] 251 Hellen AF & VA Gen Hosp, Dept Orthodont & Dentofacial Orthoped, Athens, Greece
[2] Univ Bern, Sch Dent Med, Dept Periodontol, Bern, Switzerland
[3] 251 Hellen AF & VA Gen Hosp, Dept Periodontol, Athens, Greece
[4] Univ Bern, Sch Dent Med, Bern, Switzerland
[5] Univ Bern, Sch Dent Med, Dept Orthodont & Dentofacial Orthoped, Freiburgstr 7, CH-3010 Bern, Switzerland