[1] Univ Penn, Sch Dent Med, Dept Oral Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Ctr Clin & Translat Res, Sch Dent Med, Philadelphia, PA USA
[3] Univ Penn, Ctr AIDS Res, Ctr Clin Epidemiol & Biostat, Perelman Sch Med,Div Infect Dis, Philadelphia, PA USA
[4] Univ Penn, Ctr Clin Epidemiol, Dept Biostat Epidemiol & Informat, Philadelphia, PA USA
[5] Univ Penn, Biostat Perelman Sch Med, Philadelphia, PA USA