These sharp edges may cut the side of the horse's cheeks when he chews or form ulcers on the side of the cheeks. This internal damage is painful and becomes further irritated when the rider places pressure on the bit. Horses with this problem may habitually tilt their heads and resist stopping, turning, or collection. Once you learn what the incisors should look like and how the incisors need to move in relation to the cheek teeth, it is relatively easy to determine if your horse has overgrown incisors. In most cases, you can either see the misalignment of the front teeth or hear the faulty grinding sounds.
Abnormal wear leaves the incisors uneven in length.
When the jaw moves sideways in a functional mouth the top and bottom incisors have to move apart. When the incisors are too long, the dentist will be able to slide your horse's jaw from side to side without the incisors opening at all. Another abnormal pattern is a jaw which is locked into place by faulty teeth and tight muscles. It will barely move sideways at all. There is a test you can do now, however, to listen for problems.