Asked about the incident while campaigning in Washington state, site of Saturday caucuses, the Democratic presidential hopeful reminded his questioner that he's a medical doctor.
"It's nothing I have not seen before," Dean said.
At the end of a duet Sunday, Justin Timberlake snatched off part of Jackson's bustier, revealing a breast covered only by a sun-shaped "nipple shield" to some 89 million viewers.
A spokeswoman for Jackson said a red lace garment was supposed to remain when Timberlake tore off the outer covering. But widespread questions remained about the intent. The Federal Communications Commission is investigating.