Some people report that their gum and dental health improves when they are fasting. Many forums contain crazy amounts of misinformation and claims which are unsupported by serious scientific research, so many people attribute various effects of fasting to their body being "purged of toxins" and all sorts of other nonsense.

I have noticed one of these effects on myself when I'm fasting - my teeth get somewhat sticky in the evening. The same effect is reported by many people on the aforementioned forums. On normal days when eating food, this does not happen.

It's pretty certain it's not some sticky toxins being excreted by the teeth. So what is it? I strongly suspect that it's just normal plaque, which would otherwise be abraded by chewing on food. But I always assumed that plaque is formed by food remains in the mouth, so it leads me to the question:

Is plaque formed even when one does not eat any food?

Citations of scientific literature are welcome.