AceShowbiz - Justin Bieber has a hidden flaw - he's struggling to straighten his teeth. In a new Rolling Stone expose, the "Baby" singer reveals he has been wearing a set of invisible braces on his teeth for the past year.

He explains, "They (teeth) were pointed inwards a little bit, so they had to bring them out, but when they did that, it made a small space in my teeth, and now they have to push that in... It hurts."

Also in an interview with the magazine, Bieber describes his favorite type of girls. "I like all girls," he shares. "I like a girl with a nice smile and who's funny, as far as looks, my taste is dark hair. But I don't limit myself. I like girls with blond hair too. I like everything!"