This one's a no-brainer. People chew on cold, hard ice for a variety of reasons: Out of nervousness or boredom; to kick a tobacco habit; as a substitute for something else or because they like the "invisible" taste,. In fact, there is a name for the habit of chewing ice. It's called pagophagia. It's in the family of medical conditions where people have a compulsive desire to chomp on things that have zero nutritional value like ice, clay, dirt, chalk or paint chips.
Whatever it's called, the point is crystal clear. Chewing on hard ice can wreak havoc on your teeth even more than other hard substances. Just like popcorn and hard candy, chewing ice can chip, break or crack your teeth. The habit also has the potential to wear down your teeth's enamel. If your crack or fracture is large enough, you could be in the dentist's chair prepping for a root canal or a tooth extraction.
If you're truly craving ice, you may need to check in with your doctor to make sure you are not suffering from iron deficiency anemia. If that's the case, getting treatment will help the cravings go away. You can also try drinking your beverages through a straw or order your drinks without ice so you don't even see the cubes.