Human teeth are hard formations located in the alveoli of the jaw. They are part of the apparatus, the functions of which include chewing, speech. Human teeth have a high ability to differentiate. They are much smaller in comparison with representatives of the genus monkeys.
There are four groups of teeth: molars, premolars, incisors, fangs. In dentistry, such formations are divided into lateral and anterior. A person under seven years old has temporary teeth, which then change to permanent. These figures are subject to variations, which are determined by the characteristics of nutrition and the environment. By 32 years, the last teeth of this type appear. Thus, to find out how many teeth a person can have only at a given age. This number is 32. The last teeth are often reduced, sometimes they do not erupt at all. To determine the amount of these bone formations, there is a special formula. It is called dental. In an adult, it looks like this: three molars, two premolars, one canine, two incisors from each half of both jaws.
Human teeth anatomy
Three parts of this formation are distinguished: crown, neck, root. Inside each tooth there is a cavity, which is divided into the root canal and the cavity of the crown. Through the opening of the apex, nerves and blood vessels exit, which ensure the normal functioning of this organ. They are located in the pulp, which is represented by loose connective tissue. The wall, which directly belongs to the chewing surface, is called the arch of the tooth.
In dentistry, it is customary to distinguish four surfaces of these formations: vestibular, lingual, chewing (in premolars and molars, the closure plane), and contact. The norm of position is established by direct examination. The crown and root are divided into three parts: occlusal, middle, cervical third.
Human teeth have a complex composition. They are formed by dentin, which is represented by a bone-like tissue consisting of odontoblasts. The composition of the latter includes mineral salts (calcium fluoride, magnesium phosphate, calcium phosphate) and organic fibers (collagen).
The tooth crown is covered by a particularly durable substance - enamel, which is built from prisms that have a thickness of 3-5 microns. It consists of mineral salts similar to those in dentin.
The neck and root are covered with cement - a substance that resembles bone tissue. It consists of 30% organic matter (collagen), the remaining mass is occupied by mineral salts (calcium carbonate, calcium phosphate).
All oral formations are combined under the general term: dentoalveolar system. It has a complex hierarchy and includes periodontium, muscles, joints, salivary glands, teeth. This system provides chewing functions and is involved in the formation of speech.
Antagonist teeth are the contacting formations of the upper, lower jaw. Bone organs located on the left and right side are designated as antimers.
The spatial ratio of the jaw to the dentition during all movements is called articulation. A particular type of this term is occlusion, which is determined by the closure of these formations during chewing. It is a determining factor in the formation of bite.
By this term is understood the ratio of the upper, lower dentition when the jaws are closed. The following types of bite are distinguished: alveolar arches are located on one level, one of them is located in front of the other. Physiological is the position in which the upper row of teeth is slightly shifted forward relative to the lower. However, with various pathological conditions in the oral cavity, injuries, the bite can change. Human teeth in this case can change their shape and composition.