[1] Univ Zurich, Ctr Dent Med, Clin Fixed & Removable Prosthodont & Dent Mat Sci, Zurich, Switzerland
[2] Univ Southern Calif, Ostrow Sch Dent, Lab Immunoregulat & Tissue Engn, Los Angeles, CA USA
[3] Univ Texas Hlth Sci Ctr Houston, Dept Periodont & Dent Hyg, Houston, TX 77030 USA