[1] UNIV CALIF SAN FRANCISCO, SCH MED, DEPT EPIDEMIOL, SAN FRANCISCO, CA 94143 USA
[2] UNIV CALIF SAN FRANCISCO, SCH MED, DEPT BIOSTAT, SAN FRANCISCO, CA 94143 USA
[3] UNIV CALIF SAN FRANCISCO, SCH MED, DEPT MED, SAN FRANCISCO, CA 94143 USA
[4] UNIV CALIF SAN FRANCISCO, SCH DENT, DEPT DENT PUBL HLTH, SAN FRANCISCO, CA 94143 USA
[5] UNIV CALIF SAN FRANCISCO, SCH DENT, DEPT HYG, SAN FRANCISCO, CA 94143 USA
[6] UNIV CALIF SAN FRANCISCO, SCH DENT, DEPT STOMATOL, SAN FRANCISCO, CA 94143 USA
[7] UNIV BRITISH COLUMBIA, FAC DENT, DEPT CLIN DENT SCI, VANCOUVER V6T 1W5, BC, CANADA