While some people have heard of pica - the mental health condition that causes people to want to chew or eat substances of no nutritional value such as paper, clay or dirt - fewer people have heard of a subtype of the condition called pagophagia. Pagophagia is considered less serious than pica, but is recognized as "compulsive ice chewing, which can be linked to an iron deficiency," says Dr. Roopali Kulkarni, a doctor of dental medicine and a consumer advisor spokesperson for the American Dental Association. Though the reasons for this connection are unknown, it's an association that has been studied and observed.

Of course, not everyone who chews ice has pagophagia - or any related mental health condition for that matter. But the behavior is still damaging to one's teeth and something dental professionals recommend against. 

What causes people to chew ice? 

Beyond a relatively small subset of individuals diagnosed with this craving or tendency to want to chew ice that is pagophagia, most people chew ice for a variety of other reasons. "Some people find the act of chewing ice can provide oral stimulation, similar to chewing gum," says Kulkarni. Other times, chewing ice may soothe oral inflammation such as a swollen tongue, or it may ease the effects of dry mouth, or may be done as a tactic for quitting smoking because it gives the smoker something to focus on other than a cigarette. Ice chewing may also be "a coping mechanism" for stress or anxiety, Kulkarni notes. 

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Other individuals may not even realize they are doing it. "Some people just mindlessly chew the ice left in their beverages without thinking about it," says Dr. Natalie Peterson, a doctor of dental surgery at the University of Minnesota School of Dentistry. Other times, she says, people may simply like the cooling sensation or enjoy the crunchy feeling of chewing ice. Some such people, though, may end up doing so until it "develops into a habit over time and becomes hard to stop," Peterson notes.

Some people even deliberately chew ice because they have the mistaken belief that it can benefit them. "You may be surprised about how many people think chewing ice is good for them," says Kulkarni. Some people think this because of a small study from 2014 that shows that people who ate ice performed better on tests, possibly due to the increased blood flow to the brain by constricting blood vessels. But such results have not been supported by additional research and it's more likely that the ice simply helped these test takers stay more alert the same way having a snack or chewing gum can. In any case, the cold properties of ice could still be gained by sucking on the ice until it disappears rather than chewing it.  

Is chewing ice bad for your teeth? 

No matter the reason one engages in the behavior, ice chewing is not good for the teeth. "Chewing ice can have the same negative consequences as chewing any other overly hard foods or objects," says Peterson. These risks include fracturing of teeth and associated dental work. "Fractures can be painful, which no one wants," she explains, "and repairing them can be expensive, sometimes requiring restorations like fillings or crowns to be placed." If a fracture is deep enough, it could even lead to an extraction of the tooth followed by a dental implant and crown. 

In addition to potentially causing fractures within a tooth, Kulkarni says it's also possible to chip teeth on ice because it's nearly as hard as tooth enamel. "Tooth enamel is made up of rod-like structures that are composed of thousands of microscopic crystals," she explains. "Ice is also considered a crystal, so when you push two crystals together with force, one of them will give." 

The cold temperature of ice could also cause problems for existing restorations (fillings or crowns) because those restorations "may have different rates of expansion and contraction due to temperature changes compared to your natural tooth," says Peterson. Kulkarni says engaging in the practice can also lead to an "increased sensitivity to hot and cold temperatures." 

How to break an ice-chewing habit?

If you chew ice and want to break the habit, the experts have some simple suggestions, the first of which is removing the temptation. "Try switching to drinking cold refrigerated beverages without ice in them or try letting your ice melt a bit in your drink until it becomes softer and smaller pieces," advises Peterson. She says that using a straw can also be helpful in preventing ice from entering one's mouth and becoming a temptation to chew. 

And if it's the crunch one's after, it's recommended to switch to softer crunchy foods such as raw carrots or celery instead of chewing on ice. If the habit is related to pagophagia or is a coping mechanism for stress or anxiety, seeing a mental health professional can be helpful in getting to the root of the problem. 

Talking with one's dentist can also help with understanding that any perceived benefits of the habit are likely incorrect or at least unbalanced by more downside than up. "The risks outweigh the enjoyment of chewing ice every time," says Kulkarni. "Ice is only meant for cooling, not chewing."