[1] Univ Hosp Freiburg, Dept Prosthodont, Freiburg, Germany
[2] Univ Bern, Dept Reconstruct Dent & Gerodontol, Sch Dent Med, Freibuigstr 7, CH-3010 Bern, Switzerland
[3] Univ Hosp Hannover, Dept Prosthodont, Hannover, Germany
[4] Christian Albrechts Univ Kiel, Dept Prosthodont Propaedeut & Dent Mat, Kiel, Germany
[5] Christian Albrechts Univ Kiel, Ctr Clin Studies, Kiel, Germany
[6] Univ Kiel, Inst Med Informat & Stat, Kiel, Germany
[7] Univ Med Ctr Hamburg Eppendorf, Dept Prosthet Dent, Hamburg, Germany
[8] Ulm Univ Hosp, Ctr Dent, Dept Prosthet Dent, Ulm, Germany
[9] Greifswald Univ Hosp, Dept Prosthodont Gerodontol & Biomat, Greifswald, Germany
[10] Tech Univ Dresden, Fac Med Carl Gustav Carus, Prosthodont, Dresden, Germany
[11] Heidelberg Univ Hosp, Dept Prosthodont, Heidelberg, Germany
[12] Univ Hosp Aachen, Dept Prosthodont & Biomat, Aachen, Germany