when does betty get her braces off

Betty gets her braces off in the "Ugly Betty" TV series in Season 4, Episode 17 ("Million Dollar Smile"), which originally aired on March 24, 2010. In this episode, Betty finally has her braces removed by her orthodontist, Dr. Frankel, after having them for three seasons. The event is significant enough to have a dedicated episode around it, including a dream sequence about how her life might have been without braces.