1. The McGuire Institute (Practice‐based Clinical Research Network) Houston TX USA
2. Private Practice Houston TX USA
3. Private Practice Victoria TX USA
4. Private Practice Tacoma WA USA
5. Department of Periodontics School of Dentistry University of Washington Seattle WA USA
6. Private Practice Oakbrook Terrace IL USA
7. Department of Graduate Periodontics College of Dentistry University of Illinois Chicago IL USA
8. Private Practice Boston MA USA
9. Department of Oral Medicine, Infection and Immunity Division of Periodontology Harvard School of Dental Medicine Boston MA USA
10. Private Practice San Mateo CA USA
11. Private Practice Richmond VA USA
12. Department of Graduate Periodontics Virginia Commonwealth School of Dentistry Richmond VA USA
13. Private Practice New London CT USA
14. Private Practice Fenton MI USA
15. University of Michigan School of Dentistry Ann Arbor MI USA
16. Institute for Clinical Chemistry and Laboratory Medicine Medical Center – University of Freiburg Freiburg im Breisgau Germany