What can be done to correct a slanted smile (teeth and gums)? (Photos)

Over the years dental professionals have complimented me on my straight teeth and asked if I've ever had braces. I have not :) Generally, I love my teeth. Vertically speaking, they are quite straight. Horizontally, however, my gum line and teeth are lower on my upper left side (right side in photo). Gingivoplasty didn't help. This tilt makes me feel very self conscious about my smile. Would this be best corrected by intrusion? And if so, can that be done with invisalign?