Supplements Mineral Wheel, How Long to Cause Problems?

[mufasa]

When I got my newest piggy, Amy, she had a mineral wheel in her cage, and it looked like she'd been licking it for a while. She was also on guinea pig pellets and hay, so I know she was getting decent nutrition, and I'd read here that the wheels are bad. I took it out immediately, but do I need to worry about lasting damage if she had it for a while? I read on this forum that wheels can lead to formation of bladder sludge or stones. I'd say she could have had it as long as several months if her former owners gave it to her when they got her, so I'm curious about the odds of long-term damage.

Obviously she'll never have one again. She's on her pellets and unlimited hay, plus plenty of daily veggies (which she adores).