[1] Univ Kentucky, Dept Oral Hlth Practice, Lexington, KY USA
[2] Univ Kentucky, Coll Dent, Ctr Oral Hlth Res, Lexington, KY USA
[3] Univ Kentucky, Dept Stat, Coll Arts & Sci, Lexington, KY USA
[4] Med Univ South Carolina, Coll Dent Med, Div Periodont, Charleston, SC 29425 USA
[5] Northwest A&F Univ, Coll Life Sci, Biol Teaching & Res Core Facil, Yangling, Shaanxi, Peoples R China
[6] Univ Nevada, Dept Biomed Sci, Sch Dent Med, Las Vegas, NV 89154 USA