[1] Marquette Univ Milwaukee Wisconsin, Sch Dent, Dept Clin Serv, Milwaukee, WI USA
[2] Univ Nebraska Med Ctr, Coll Publ Hlth, Dept Biostat, Omaha, NE USA
[3] Univ Wisconsin, Joseph J Zilber Sch Publ Hlth, Milwaukee, WI USA
[4] Boston Univ, Henry M Goldman Sch Dent Med Massachusetts, Dept Hlth Policy & Hlth Serv Res, Boston, MA USA
[5] Med Coll Wisconsin, Inst Hlth & Equ, Div Biostat, Milwaukee, WI USA
[6] Marquette Univ Sch Dent, Dept Clin Serv, Room 356,POB 1881, Milwaukee, WI 53201 USA