1. Department of Epidemiology; Gillings School of Global Public Health; University of North Carolina at Chapel Hill; Chapel Hill NC USA
2. Department of Dental Ecology; School of Dentistry; University of North Carolina at Chapel Hill; Chapel Hill NC USA
3. Department of Biostatistics; Gillings School of Global Public Health; University of North Carolina at Chapel Hill; Chapel Hill NC USA
4. Department of Periodontology; School of Dentistry; University of North Carolina at Chapel Hill; Chapel Hill NC USA