1. Center of Dental Medicine; Clinic of Masticatory Disorders, Removable Prosthodontics, Geriatric and Special Care Dentistry; University of Zurich; Zurich Switzerland
2. Departments of Orthodontics & Dentofacial Orthopedics, and Oral & Craniofacial Sciences; School of Dentistry; University of Missouri-Kansas City; Kansas City MO USA
3. Department of Oral Diagnostic Sciences; School of Dental Medicine; University at Buffalo; Buffalo NY USA
4. Department of Statistics; University of Nebraska-Lincoln; Lincoln NE USA