TY  - JOUR 
T1  - Clinical trial registration: now required
JO  - Brazilian Oral Research
A1  - Lotufo, Mônica Andrade
SN  - 1806-8324
UL  - 10.1590/S1806-83242008000200001
VL  - 22 
Y1  - 2008
PB  - Brasil 
ER  -