How can I get rid of this weird dent when I smile? (photos)

I really hope someone can help me. I'm getting married next year but hate smiling due to a weird dent that appears when I smile. It shows on the right-hand side only; I first noticed it about five years ago when I was thirty. It's like a small pocket of fat bunches at the side of my mouth and creates an ugly vertical line when I smile. I saw someone about having fillers but they said this wasn't possible as you can't see the line when my face is resting, only when I smile. Can anything be done?!