I've had luck taking vitamin K2, the mk-4 form known as menatetranone. I happen to take carlson k2. After about a week, my plaque softened dramatically. It usually comes off by brushing with baking soda and flossing.
If I get some build-up I use a magnifying mirror and a dental scaler (from a "dental cleaning kit" I bought at the drug store for five dollars) to clean my teeth. I've been taking mk-4 and vitamin D daily for about 4 years and my plaque is consistently soft and easy to remove.
By the way, I've heard that the mk-7 form of vitamin K2 known as menaquinone does not work on dental plaque, but I haven't tried it so can't say for sure.