[1] Univ Zurich, Clin Fixed & Removable Prosthodont & Dent Mat Sci, Zurich, Switzerland
[2] Med Univ Graz, Sch Dent, Dept Oral Surg & Radiol, Graz, Austria
[3] Univ Zurich, Ctr Dent Med, Clin Prevent Dent Periodontol & Cariol, Zurich, Switzerland
[4] Yonsei Univ, Res Inst Periodontal Regenerat, Dept Periodontol, Coll Dent, Seoul, South Korea