Jennifer Connelly’s first topless scene in The Hot Spot (1990)
The film was lensed from August 14, 1989 to October 21, 1989. Connelly was 18 at the time!
If this scene had been released in the internet age, I think it would have been bigger than Katie Holmes in The Gift, which was a cultural phenomenon. Even without the internet, it must have caused a sensation with the male population. (I can’t say for sure. I was living overseas at the time.)
I don’t remember if you had Jennifer Connelly on your list of sexiest non-nude performances, but her wearing a tight tank top in the 1991 film Career Opportunities seemed to be an even bigger sensation than her topless scene in The Hot Spot.