I think when the body is detoxing, some gnarly stuff detoxes through the relatively thin membranes in the mouth, resulting in extra plaque. I’ve noticed this in past cleanses I’ve done, even before I started dealing with candida, but I also noticed it near the beginning of my candida treatment.
If you feel like you have gritty teeth after eating greens, it’s usually due to oxalic acid crystals. Oxalic acid isn’t water-soluble, so they can scrape around inside your mouth a little. They’re the reason some people have an itchy gums/lips reaction to eating raw chard or raw spinach.