Yes! There has been links between heart health and more recently Brian health (Alzheimer's). A quick search will show up some of these studies 🙂
I know that flossing removes food particles that would otherwise(even after brushing) remain stuck between teeth and could cause a cavity in the long run. I hope this helped you!
While I can't quote sources, I'm sure there are proven benefits. Just look at all that crud stuck between your teeth if you haven't flossed for a while.