[1] Univ Bern, Sch Dent Med, Dept Oral Surg & Stomatol, CH-3010 Bern, Switzerland
[2] Univ Hawaii, John A Burns Sch Med, Dept Anat Biochem & Physiol, Honolulu, HI 96822 USA
[3] Univ Basel Hosp, Inst Clin Epidemiol & Biostat, CH-4031 Basel, Switzerland