I have in the past used that hydrogen peroxide gargle too.
However, I was reading about using a combo Hydrogen Peroxide and iodine nebulizer treatment. It was not effective against the coof without the iodine though.
Most tooth whitening mouthwash has hydrogen peroxide in it. It kills bacteria that causes plaque and softens the plaque as well. I use it and not for the tooth whitening. Listerine is the best.
-SB