he Loves his kitty litter too much

Has anyone out there had a cat who tries to eat the cat litter? I have a very old cat. For most of his life, he ate Cat Chow. A few years ago, he developed severe dental issues and now has one tooth left. So he's been on canned food since then. I recently switched him over to raw food, which he seems to like, but something's missing apparently.

I've caught him several times eating litter. First and most important: is this dangerous, or will it pass through? (his stools seem normal, if a bit grayer) I noticed that the litter I was using at the time smelled kinda minty, so I switched it out for unscented. He doesn't go for it as often, but when he does, he doesn't quit. And it's not like I can watch him 24/7 or restrict his access to litter box.

I've tried putting down some Cat Chow, thinking that he misses the crunchy, but he took a couple of bites and went for the litter box. :fust

I've tried not fully cleaning the box, so he'd be less enticed (?) I left the last bit where his head is usually at when he does his business. So he piddled outside the box with his head in the middle. I'm very glad I put the box on a mat.

One time I caught him eating it and I pulled him out of the box. So then he did the 'gonna go here' pose, so I put him back in the box. He promptly started munching, so I pulled him out again and he dropped a deuce right on the bed. :fust

Thoughts? Suggestions?
Thanks in Advance,
Jamie