[1] NIAMSD, NIH, Bethesda, MD 20892 USA
[2] Virginia Commonwealth Univ, Sch Dent, Dept Periodont, Richmond, VA USA
[3] Ohio State Univ, Coll Dent, Div Biosci, Columbus, OH USA
[4] Univ Penn, Div Pediat Dent, Sch Dent Med, Philadelphia, PA USA
[5] Univ Maryland, Sch Dent, Div Periodont, Baltimore, MD 21201 USA