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