1. Department of Oral Biology, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
2. Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
3. Lieutenant Colonel, US Army DENTAC, Brooke Army Medical Center, Fort Sam Houston, San Antonio, TX 78234-5004, USA