1. Clinical Sciences Department, Ajman College of Dentistry, Ajman University, Ajman City P.O. Box 346, United Arab Emirates
2. Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, 3010 Bern, Switzerland
3. Department of Prosthodontics, The University of Iowa College of Dentistry and Dental Clinics, Iowa City, IA 52242, USA