[1] Univ Tehran Med Sci, Sch Dent, Dept Community Oral Hlth, Tehran, Iran
[2] Univ Helsinki, Inst Dent, Dept Oral Publ Hlth, Helsinki, Finland
[3] ACECR, Hlth Metr Res Ctr, Iranian Inst Hlth Sci Res, Mental Hlth Res Grp, Tehran, Iran
[4] Univ Oulu, Inst Dent, Dept Community Dent, Oulu, Finland
[5] Oulu Univ Hosp, Oral & Maxillofacial Dept, Oulu, Finland