1. Department of Preventive Sciences, King Abdulaziz University Faculty of Dentistry, Jeddah, Saudi Arabia
2. Department of Health Policy & Health Services Research, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
3. VA Boston Healthcare System, Boston, MA, USA
4. Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
5. Department of Periodontology & Oral Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA