My passport (book) photo from 2009 has me with a smile showing teeth. TSA Officer in 2011 when I presented it to them said "you know, your photo doesn't meet the rules, you can't smile in passport photos". I just shrugged and that statement was the end of it.
My passport book photo taken two years later, I was told, no teeth showing, so that was fine.
My GE photo from 2013 was taken at DTW on one of those Logitech orbit webcams (one of those ancient ones in a spherical shape, a little ball on a plastic stand). The photo is horrible due to the abysmal quality of the webcam - the right side of my face is distorted and is bigger than the left, it's slightly askew (tilted), and my teeth are showing (actually, the CBP officer encouraged me to smile). No TSA personnel has ever commented on it, and for domestic travel, it's always the ID I present at the checkpoint.