Speaking from experience, chewing ice can really cause tiny cracks in your teeth. Those tiny cracks can, over time, especially with continued ice chewing turn into BIG, painful, chip-off-a-chunk of tooth, very-expensive-to-fix cracks.
My dentist always warned me...
Finding a good substitute to ice chewing seems important. It is hard to give up a habit if you don't replace it with something else. Carrots, celery, gum...
Good luck!