as milk, temporary, or baby teeth) soon after birth, with these being replaced by permanent teeth by the age of approximately five years old. The horse will normally have 24 deciduous teeth, emerging in pairs, and eventually pushed out by the permanent teeth, which normally number between 36 and 40. As the deciduous teeth are pushed up, they are termed "caps". Caps will eventually shed on their own, but may cause discomfort when still loose, requiring extraction. It is possible to estimate the age of a young horse by observing the pattern of teeth in the mouth, based on which teeth have erupted, although the difference between breeds and individuals make precise dating impossible. All teeth are normally erupted by the age of five, at which point the horse is said to have a "full mouth", but the actual age this occurs will depend on the individual horse, and also by breed, with certain breeds having different average eruption times. For instance, in Shetland ponies the middle and corner incisor tend to erupt late, and in both draft horses and miniature horses, the permanent middle and corner incisors are usually late appearing. Tooth wear Horse teeth often wear in specific patterns, based on the way the horse eats its food, and these patterns are often used to conjecture on the age of the horse after it has developed a full mouth. As with aging through observing tooth eruption, this can be imprecise, and may be affected by diet, natural abnormalities, and vices such as cribbing. The importance of dentition in assessing the age of horses led to veterinary dentistry techniques being used as a method of fraud, with owners and traders altering the teeth of horses to mimic the tooth shapes and characteristics of horses younger than the actual age of the equine. Equine teeth have evolved to wear against the tooth above or below as the horse chews, thus preventing excess growth. The upper jaw is wider than the lower one. In some cases, sharp edges can occur on the outside of the upper molars and the inside of the lower molars, as they are unopposed by an opposite grinding surface. These sharp edges can reduce chewing efficiency of the teeth, interfere with jaw motion, and in extreme cases can cut the tongue or cheek, making eating and riding painful. In the wild, natural foodstuffs may have allowed teeth