Our teeth erupt and stay that length for their life of the tooth. The horse's teeth are constantly erupting until they expire or fall out in nearly 25-30 years. The teeth don't meet perfectly as they grind their food and wear the teeth. The uneven meeting of the teeth causes some parts of the teeth to be worn unevenly and the motion of the jaw in which the horse chews causes uneven wear. Sharp edges tend to form on the upper teeth on the cheek surface and on the lower surface on the tongue surface edges. Where the teeth don't meet and grind they continue to erupt and become very uneven causing the normal movement in the jaw to become difficult. If a horse looses a tooth the opposing tooth will erupt into that space because of lack of wear. All this uneven wear and constant eruption causes much discomfort and poor performance along with improper chewing of their food. By properly correcting this with bite readjustment the horse will do better in performance, health and comfort.