I have worked and filmed with many famous actresses, including some of the Bollywood stars mentioned in other answers here. They all smile beautifully, and they all smile professionally to perfection, to camera and to an audience.
However, away from the camera there is one Bollywood actress who still retains an incredibly beautiful smile, even without make up and beauty lighting, here she is:
Manjari Fadnis has an incredible smile, and even after many hours working in the water at sea, she still retains a perfect smile to everyone, with no effort.
Here another stolen moment on location after a very long day:
And here she is in Bollywood style:
The best smile is the one that stuns you even without make up, without beauty lighting and all the tricks we use as cinematographers to give glam to actresses, a sincerely intelligent and at the same time childlike expression, that touches every heart, even the one of a hardened pro like myself, who knows all the tricks.