[1] ERGOPerio, European Res Grp Periodontol, Genoa, Italy
[2] Univ Hong Kong, Dept Periodontol, Fac Dent, Hong Kong, Hong Kong, Peoples R China
[3] Univ Bonn, Dept Periodontol, Bonn, Germany
[4] Univ Calif Los Angeles, Dept Periodontol, Los Angeles, CA USA