Did you ever wonder why, when the dry season comes, grass merely turns yellow but does not wilt like your houseplants do when they need water? Grass blades are internally supported by a ladder-like "skeleton" of silica. This is in addition to cell walls like those which make a stalk of celery stiff. Silica is what a pane of glass is made of, or quartz rock, or sand. With every mouthful of food he takes, it is as if your horse has to chew up a certain amount of ground glass.

The length of the crowns of the teeth in horses is much greater than in people. Most of the length of your horse's cheek teeth is "stored" within his upper and lower jaws. Only about 1/2 inch of each cheek tooth actually protrudes from the gum. As grass wears the teeth, they push out from their sockets like lipsticks. The pressure of chewing helps the body regulate the rate at which the teeth push out.

In the wild, when an animals's teeth wear out, it dies. Long tooth crowns are the main factor that compensates for the abrasive silica in grass, and thus in the wild, are the ultimate determinant of a horse's lifespan. Domestic horses can be kept alive on special feeds even after all teeth have worn out. However, this is a last resort. Modern equine dentistry can significantly extend the useful lifetime of your horse's teeth as well as enhance his comfort and your safety under the artificial condition of bitting.