1. Department of Biomedical Sciences; Texas A&M College of Dentistry; Dallas Texas 75246
2. Department of Applied Prosthodontics; Graduate School of Biomedical Sciences, Nagasaki University; 1-7-1 Sakamoto Nagasaki 852-8588 Japan
3. Division of Periodontology; University of California; San Francisco California 94143
4. Department of Periodontology and Implant Dentistry; College of Dentistry, New York University; New York New York 10010