1. Department of Anatomy and Neurobiology, College of Medicine, MN 210 Chandler Medical Center, University of Kentucky, Lexington, KY 40536, USA
2. Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
3. Department of Statistics, University of Kentucky, Lexington, KY 40536, USA
4. Department of Biostatistics, University of Kentucky, Lexington, KY 40536, USA
5. Department of General Dental Sciences, School of Dentistry, Marquette University, Milwaukee, WI 53201, USA
6. University of Kentucky College of Dentistry, Chandler Medical Center, Lexington, KY 40536, USA