1. CEMRO Periodontics Department, Morelia 58880, Mexico
2. Department of Prosthodontics, University of Iowa College of Dentistry, Iowa City, IA 52242, USA
3. Department of Restorative Dentistry, University of Manitoba Dr. Gerald Niznick College of Dentistry, Winnipeg, MB R3E 0W2, Canada
4. Division of Restorative Dental Sciences, Clinical Sciences Department, Ajman College of Dentistry, Ajman City P.O. Box 346, United Arab Emirates
5. Department of Reconstructive Dentistry and Gerodontology, University of Bern School of Dental Medicine, 3010 Bern, Switzerland
6. Department of Operative Dentistry, University of Iowa College of Dentistry, Iowa City, IA 52242, USA
7. Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE 68102, USA