[1] Sigmund Freud Univ Vienna, Fac Med, Dept Periodontol, Dent Clin, Vienna, Austria
[2] Univ Malmo, Fac Odontol, Dept Periodontol, Malmo, Sweden
[3] Copenhagen Univ Hosp Amager & Hvidovre, Med Div, Gastrounit, Hvidovre, Denmark
[4] Copenhagen Univ Hosp Amager & Hvidovre, Copenhagen Ctr Inflammatory Bowel Dis Children Ado, Hvidovre, Denmark
[5] Univ Bern, Sch Dent Med, Dept Orthodont & Dentofacial Orthoped, Bern, Switzerland
[6] Karolinska Inst, Dept Dent Med, Div Oral Dis, Stockholm, Sweden
[7] Med Univ Vienna, Univ Clin Dent, Div Conservat Dent & Periodontol, Vienna, Austria
[8] Univ Malmo, Fac Odontol, Dept Periodontol, Carl Gustafs Vag 34, S-20506 Malmo, Sweden