1. Department of Cariology and Endodontology, Peking University School of Stomatology, Beijing, China
2. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
3. Department of Periodontics, University of Washington, Seattle, Washington, USA
4. The Forsyth Institute, Cambridge, Massachusetts, USA
5. Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA