I have an idea that may explain some of our need for excessive ice crunching. It's a disorder (actually a set of characteristics) called sensory defensiveness. What happens is your nervous system becomes overloaded from stress from sensory input around you (noises, smells, etc.) or just plain stress and then your nervous system craves a way to calm you. It is similar to swaddling a colicy baby who is over-stressed (crying) and even to then giving that baby a bottle/nursing him. Oral-motor movement especially with deep pressure like crunching (also chewing, biting, grinding teeth, or sucking with pressure like thru a narrow straw or bottle nipple) gives great input that is calming to our nervous systems. Is this bad? Not necessarily, but I'd venture to say that the teeth of ice crunchers are not usually the best after years of the habit. So what can you do it you want to stop? Try some substitute things (sort of like smokers use gum chewing to stop) like chewing foods like beef jerky, gum, skittles, eating crunchy things like carrots or chips, or drinking through a straw. The most powerful oral-sensory input can be received if the foods are sour (like sour skittles or lemons) or minty (like Big Red gum or altoids), so keep that in mind. The other idea is to meet the need through a whole-body deep pressure technique (again like the infant swaddling) such as by wrapping up really tightly in a soft blanket, jumping for several minutes, etc. Hope this is informative.