Dentes molares: Grasping that ferrets are obligate, primary carnivores, that is, mammals that primarily eat animal prey and are physiologically required to do so in order to survive, it might seem incongruous that after millions of years of evolution they would still possess molars. For example, many felids have lost their molars, and in many instances, cats are not as carnivorous as ferrets (or rather, their polecat progenitors). It is precisely because ferrets are obligate, primary carnivores that they retain their molars; they are an important aspect of the dental apparatus used to render animal flesh, and are not designed to grind food. Ferrets have two upper and four lower molars. The 1st maxillary molar (= M1/, upper molar, maxillary grinder, cheek tooth) is turned roughly perpendicular to the rest of the dental arcade, and is reduced compared to the rest of the dentition. It is essentially shaped like an irregular oval with a slightly pinched "waist." The portion nearest the vestibular surface (= buccal surface) supports a pair of cone-like cusps, with the lingual portion flatter and having a slightly raised rim. The 1st mandibular molar (= M/1, lower first molar, sectorial tooth; carnassial, cheek tooth) is modified into the lower carnassial. The blade is divided into two points separated by a deep notch. The distal portion of the carnassial is flattened into a ledge, supporting a cusp that is aligned with the medial portion of the maxillary molar. The 2nd mandibular molar (= M/2, lower second molar, cheek tooth, grinder) is greatly reduced; even in large males it is usually only about an eighth of an inch in diameter. The molar is roughly shaped like the head of a pin, with a single cone-like cusp on top. The 2nd mandibular molar sits directly behind the lower carnassial, and aligns with the distal part of the upper molar. The cone-like cusps of the upper and lower molars are offset to each other, so they line up like the serrated jaws in a pair of pliers. However, the teeth are not designed to grip, nor are they designed to grind. Rather, they are designed to be a miniature anvil and hammer, perfect for crushing small bones, hard insect and crustacean exoskeletons, snail shells, and other hard objects that may contain nourishment the ferret is obliged to obtain. This is accomplished elegantly by ferrets, which use extreme biomechanical force to drive the small point of a cusp into the material, shattering it in the same general location as being sheared by the carnassial. As the ferret slices the flesh and impacts a bone, it will slide down the blade of the carnassial and come to rest against the cusps on the molars. The molar cusps stabilize the bone, preventing it from moving as the pointed cusp of the upper molar is driven into the surface by the powerful jaw muscles. This occurs in the rear of the jaw, where the biomechanical forces are the greatest. Small long bones, such as those found in frogs, birds, rodents and rabbits, are shattered into tiny fragments that remain imbedded in surrounding tissue, and are safely swallowed. In wild polecats, the molars will exhibit moderate wear, with the cusps losing their points in older animals. In contrast, this is not the case in pet ferrets fed dry kibbled or extruded foods. Dry foods cause extensive wear to the molars for three basic reasons; the foods are very hard, they are solid rather than being essentially hollow, and they are not cushioned from direct impact with the teeth. Dry foods are guaranteed to be 10% moisture or less, which is instrumental in the creation of a hard, crunchy food that can remain in the bowl for days without worry of purification. There is no question that some of the foods consumed by wild polecats are harder than these dried foods; nonetheless, it is also true that few of those hard foods become the single component of a life-long diet. Part of the problem is that ferret teeth never evolved the strength to consume a hard diet for long periods of time; the enamel shell surrounding the dentine core is rather thin. This is exacerbated by two other factors. First, the hard foods wild polecats may consume are essentially hollow; that is, they are composed of a hard shell surrounding a softer interior, such as bones, insects, and snails. When the jaws apply pressure, the bone (or exoskeleton) collapses inwardly, which results in less wear than caused by crunching a solid food pellet possessing "homogenized hardness." The problem is exacerbated by a lack of cushioning, such as when muscle and connective tissue surrounds a bone. For the zooarchaeologist, the result is that it is a simple task to differentiate between wild polecats and pet ferrets, based wholly on the wear to the molars. In pet ferrets, the maxillary molar is brutally impacted by commercially manufactured dried foods, and is severely worn by the time the ferret is three or four years old. Few ferrets older than four years of age retain cusps on their molars; indeed, it is quite common for the crowns to be completely worn away, exposing the internal dentine structure. In many cases, the maxillary molar is so worn that the tooth breaks at the "waist", or even to the point that the only remaining portions of the molar are the exposed roots. This is also seen in the 2nd mandibular molar, which is so commonly worn to the roots that in many pet ferret skulls, all that can be seen is the rod-like root, sticking out of the jawbone to the level of the gum line. In all of the black-footed ferret, steppe and European polecat, New Zealand feral ferret, and pet domesticated ferret skulls I have examined, this type of extreme wear is only found in pets fed hard commercial foods. Molars are also subject to gingival and periodontal disorders, and the 2nd mandibular molar is frequently lost as a result. Occasionally, a 2nd mandibular molar will become impacted, that is, it cannot normally erupt because of overlying bone or an adjacent tooth, but this is relatively infrequent. With extreme wear comes microfractures, which provide access points for the bacteria which cause caries; not uncommonly found in the molars. On occasion, the molars will be malformed. This is especially true in the maxillary molars, which can exhibit a wide range of morphology. On very rare occasions, the maxillary molar will be lost; a condition more commonly seen in the case of the 2nd mandibular molar. Adult ferrets have a total of six molars; two each in the maxillary quadrants, and one each in the mandibular quadrants. Dentes molares (= M, m, molar, grinder, cheek tooth, posterior tooth, postcanine tooth, grinding tooth, sectorial tooth, carnassial) [Posted in FML issue 3519]