I've been hugely lazy about brushing Leia's teeth since signing her up for a dental. You can imagine how surprised and pleased I was to see the huge chunk of calculus missing from Leia's tooth. This is especially impressive because I went through great lengths (contacting the C.E.T. toothpaste company, various vets, etc.) in order to determine whether or not toothbrushing will help remove the build up. (It won't) which leaves the raw food as the potential cause of this calculus removal.
What's particularly impressive to me is that Leia doesn't chew. Nothing presses on her teeth hard enough to pull that crap off. I've tried with my fingernails. She is offered bones but never takes them. This is all enzyme action I think.