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The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. [1] [2] [3] They have at least two cusps. Premolars can be considered transitional teeth during ...
Universal numbering system. This is a dental practitioner view, so tooth number 1, the rear upper tooth on the patient's right, appears on the left of the chart. The Universal Numbering System, sometimes called the "American System", is a dental notation system commonly used in the United States. [1] [2]
Diagram of tooth anatomy. Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. (The function of teeth as they contact one another falls elsewhere, under dental occlusion.)
The maxillary teeth are the maxillary central incisors (teeth 8 and 9 in the diagram), maxillary lateral incisors (7 and 10), maxillary canines (6 and 11), maxillary first premolars (5 and 12), maxillary second premolars (4 and 13), maxillary first molars (3 and 14), maxillary second molars (2 and 15), and maxillary third molars (1 and 16).
The system uses two numbers to define each tooth. One to specify the quadrant, and one to specify the tooth within that quadrant. Orientation of the chart is traditionally "dentist's view", i.e. patient's right corresponds to notation chart left. The designations "left" and "right" on the chart below correspond to the patient's left and right.
The upper teeth are denoted I 1, I 2, C −, Pm 3, Pm 4, M 1, M 2, and M 3. Left or right has to be specified. The lower teeth are I 1, I 2, C −, Pm 3, Pm 4, M 1, M 2, and M 3. The reason the premolars are labeled 3 and 4 is that in earlier primates there were two other premolars between them and the canines. [5]
Carnassial teeth are modified molars (and in the case of carnivorans premolars) which are adapted to allow for the shearing (rather than tearing) of flesh to permit the more efficient consumption of meat. These modifications are not limited to the members of the order Carnivora, but are seen in a number of different mammal groups.
Regarding premolars, there is disagreement regarding whether the third type of deciduous tooth is a premolar (the general consensus among mammalogists) or a molar (commonly held among human anatomists). [8] There is thus some discrepancy between nomenclature in zoology and in dentistry.