In humans, the canine teeth are the main components in occlusal function and articulation. In other mammals such as some primates, they are used to split open hard-surfaced food. In carnivores, they are primarily offensive weapons for bringing down prey. In many mammals, the canines are pointed, tusk-shaped teeth, projecting beyond the level of the other teeth. The canines are immediately behind the incisors. Their function is cutting, slicing, or gnawing food into manageable pieces that fit into the mouth for further chewing. They are normally flat, chisel-shaped teeth that meet in an edge-to-edge bite. The incisors occupy the front of the tooth row in both upper and lower jaws. These are the incisor ( cutting), the canine, the premolar, and the molar ( grinding). "They 'occlude', that is, the chewing surfaces of the teeth are so constructed that the upper and lower teeth are able to fit precisely together, cutting, crushing, grinding or tearing the food caught between." Īll mammals except the monotremes, the xenarthrans, the pangolins, and the cetaceans have up to four distinct types of teeth, with a maximum number for each. The teeth in the upper and lower jaws in mammals have evolved a close-fitting relationship such that they operate together as a unit. The mammalian pattern is significantly different. Since the origin of teeth some 450 mya, the vertebrate dentition has diversified within the reptiles, amphibians, and fish: however most of these groups continue to possess a long row of pointed or sharp-sided, undifferentiated teeth ( homodont) that are completely replaceable. Despite this debate, it is accepted that vertebrate teeth are homologous to the dermal denticles found on the skin of basal Gnathostomes (i.e. Current theories suggest either an "outside-in" or "inside-out" evolutionary origin to teeth, with the dentition arising from odontodes on the skin surface moving into the mouth, or vice versa. The evolutionary origin of the vertebrate dentition remains contentious. The dentition of animals in which the teeth are set in sockets in the jawbones is termed thecodont. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed polyphyodont. The dentition of animals with two successions of teeth ( deciduous, permanent) is referred to as diphyodont, while the dentition of animals with only one set of teeth throughout life is monophyodont. Īnimals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have homodont dentition, whereas those whose teeth differ morphologically are said to have heterodont dentition. That is, the number, type, and morpho-physiology (that is, the relationship between the shape and form of the tooth in question and its inferred function) of the teeth of an animal. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. Cast of a human upper jaw showing incisors, canines, premolars, and two of the three possible sets of molars.ĭentition pertains to the development of teeth and their arrangement in the mouth. Not to be confused with Detention (disambiguation).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |