[1] Univ Dundee, Sch Dent, Dundee DD1 4HR, Scotland
[2] Univ Hong Kong, Fac Dent, Hong Kong, Peoples R China
[3] Univ Michigan, Sch Dent, Cariol & Restorat Sci, Ann Arbor, MI 48109 USA
[4] Univ Otago, Sch Dent, Dept Oral Sci, Dunedin, New Zealand
[5] Univ Austral Chile, Sch Dent, Valdivia, Chile
[6] Charite Univ Med Berlin, Dept Oral & Maxillofacial Surg, Berlin, Germany
[7] Univ Bonn, Periodontol Operat & Prevent Dent, Bonn, Germany
[8] Charite Univ Med Berlin, Operat & Prevent Dent, Berlin, Germany