My dental hygienist just recently gave me a small wire brush that's reusable (size zero) that you can stick between your teeth and rub back and forth to dislodge the plaque that's hard to get with a regular brush or floss. It's changed my life. I love it so much, and I no longer see that significant plaque buildup between my bottom two front teeth.
I use plain old waxed dental floss. If I can get something made out of natural fibers, I will purchase that. I worry about the amount of plastic in the environment.