"I was sitting on the bed with my mom and my sister, and they're like, 'You're an idiot. You did not. Come on,' " Duff, 23, says in an interview airing Monday on The Ellen DeGeneres Show.
The actress-singer, who tied the knot with longtime hockey player beau Mike Comrie, 30, in August, says her dental dilemma happened at about 11 a.m. on her wedding day, just three hours before she needed to start getting ready.
"I burst into tears," she says. "Then I started laughing at myself, and then I really burst into tears."
So who saved her big day? Her wedding planner, whose sister's husband's best friend is a dentist in Montecito, Calif.
Gap tooth-grin evasion aside, her romantic, candlelit ceremony went off without a hitch.
"The actual wedding was perfect," she says. "Thank God I didn't swallow [my tooth]. Not good for a bride on her wedding day."