The graphic representation on the left shows the approximate positioning of the 'crowns' of the teeth in the horse's mouth. The incisors, canines, wolf teeth and molars are shown. You can see that the incisors (front teeth) and the molars are matching properly and there is no overlap. When the bite is also examined from the front of the mouth and the angles of all the chewing surfaces are symmetrical as shown below, then the bite, and therefor the wear, is considered normal.
When the bite is normal the feed moves efficiently up towards the back of the mouth as it is being chewed. As all the molars have about the same length there is no impediment to feed moving up along the molars and feed is ingested at a normal rate. The picture on the left shows how the cheek muscle is located alongside the back 2-3 molars. In the right diagram it is shown how much narrower the lower molars are than the upper molars. As well as that the lower jaw is much narrower than the upper jaw.