[1] Univ Warwick, Warwick Med Sch, Div Hlth Sci, Coventry, England
[2] Univ Ibadan, Coll Med, Fac Dent, Dept Periodontol & Community Dent, Ibadan, Oyo, Nigeria
[3] Univ Coll Hosp UCH, Ibadan, Oyo, Nigeria
[4] Univ Birmingham, Inst Appl Hlth Res, Coll Med & Dent Sci, Birmingham, England
[5] Fed Univ, Fac Social Sci, Dept Psychol, Oye Ekiti, Nigeria
[6] Univ Ibadan, Coll Med, Fac Dent, Dept Restorat Dent, Ibadan, Oyo, Nigeria
[7] Univ Ibadan, Coll Med, Dept Community Med, Fac Publ Hlth, Ibadan, Oyo, Nigeria
[8] Univ Ibadan, Coll Med, Fac Clin Sci, Dept Obstet & Gynaecol, Ibadan, Oyo, Nigeria
[9] Amgen Inc, Ctr Observat Res, Thousand Oaks, CA USA