P. Kraivaphana
C. Amornchata
T. Triratanaa
L.R. Mateob
R. Ellwoodc
D. Cumminsc
W. DeVizioc
Y.-P. Zhangc
aFaculty of Dentistry, Mahidol University, Bangkok , Thailand;
bLRM Statistical Consulting, Hoboken, N.J.
cColgate-Palmolive Technology Center, Piscataway, N.J. , USA
