Tooth

Vocabulary

Indo-European root donts . One speaks about palatine teeth when they are enchased in the Palais, of the lingual teeth on the language, and about teeth vomériennes when they are enchased in the Vomer while teeth related to the jaw, as for the Mammifère S are teeth jawbones.

The bones on the level of the throat can some qualified times being of teeth pharyngiennes.

Description

It is the hardest body of the organization because it is made of ivory. It resists fire a long time and is used thus for the identification in medico-legal Médecine.

Its body is mainly made up of Dentine. This fabric is mineral-bearing to 70% by the hydroxyapatite. The 30% remainder (of which water 12%) constitute the organic screen, primarily made up of Collagène. The dentine is perforated dentinal microphone-tubes or tubulis. Those contain the prolongations of the dental cells, the Odontoblaste S. These cells paper the periphery of the pulp cavity. They synthesize the dentine throughout the life, in a centripetal way, and at very slow intervals.

The pulpar fabric ensures their innervation and their vascularization coming from the dental roots. The Odontoblaste S synthesize in answer to the carieuse aggression a reactional dentine.

The crown is covered with enamel, fabric mineralized with more than 97%. It is less thick on the temporary teeth. The root is covered with Cément, where are enracinent the collagenic and elastic fibers alvéolo-dental ligament or Desmodonte.

This ligament constitutes with the bone a true articulation and contains cells of osseous regeneration, ligamentaire and cémentaire. It is richly innervé by mechanical receivers, proprioceptors, which inform the central Nervous system about the exact position of the teeth and the pressure exerted by the Muscle S masticateurs.

The tooth is established in the alveolar Os by one to three root S (sometimes more). The dental roots end in a apex whose opening of less than 1 mm allows the vascularization and the innervation of the tooth (by the nerve mandibulaire).

The teeth are carried by the jawbone (upper jaw) and the mandible (jaw lower).

Roles

The teeth have several big roles:

Food: the Incisive S make it possible to divide the Aliment S (or another thing); the Molar S and Prémolaire S allow the Mastication, the crushing of food; the canines make it possible to shred food like the meat (see the Carnivores and their canines).
Phonetic: the teeth, in partnership with the Language and the Lip S, make it possible to pronounce many Phonème S
Esthétique: they support the soft fabrics which surround them (lips, cheeks).

When they are absent, one attends the depression of the lower stage of the face (the Mandibule “goes up” and advances, the Lèvre S are inserted): it is the profile of the toothless old man. This phenomenon is accentuated by the disappearance of the alveolar Os. This bone exists by and for the tooth, and " fond" gradually when, with the tooth, mechanical stimulation disappears. Certain species have teeth which exceed out of the mouth.

Attack and Defense, for many animals: they are weapons.

Various types of teeth

the Incisive S. One has 8 of them (4 central incisors, 4 side incisors). They are the teeth of the smile. They are monoradiculées, like the canines.
the Canine S. One has 4 of them. It is the tooth having the longest root, single. It allows the désocclusion of the other teeth at the time of the movements of chewing, thus protecting them from excessive and nonphysiological forces; they are absent at the herbivorous species.
the Prémolaire S. One has 8 of them too. They have one or two roots, very seldom three.
the molar S. One has some from 8 to 12 (according to whether the wisdom teeth are formed or not). They are the teeth of the chewing, most solid. They generally have 3 roots.

One also speaks about Tooth wisdom, the third molar which pushes starting from the fifteen years age at the Homme. It is increasingly rare to have its four wisdom teeth; often there are only two of them or three to be formed and they always do not have the place necessary to a correct positioning, in which case they cause Infection S with repetition (péricoronarite, cellulitis) and must be removed.

At the Man, two Dentition S follow one another:

the temporary teeth or teeth baby : they start to push around 6 months (but that can go from the birth up to one year). They start to fall around 6 years. There are twenty of them.
the final teeth or permanent teeth: the first to be left in mouth is the first molar, around 6 years. Then the order is variable. The last final teeth are set up around 12 years with the eruption of the 2nd final molars. One can have 32 in very of them if his four wisdom teeth are had.

Classification

To simplify the communication, the International Dental Fédération allots to each tooth a number:

For the figure of the units: one numbers the teeth on the basis of the center towards the bottom.

1 the central incisor,
2 the side incisor,
3 the canine,
4 the first premolar,
5 the second premolar,
6 the first molar,
7 the second molar,
8 the wisdom tooth.

the figure of tens is determined by the part of an imaginary quadrant in which the tooth is. By looking at the person opposite, 1 is in top on the left, 2 in top on the right, 3 bellow on the right, 4 bellow on the left.
For the temporary teeth, the figure of tens is from 5 to 8 according to the same quadrant, in the direction of the needles of a watch.

Examples: 23 are the left higher canine; 74 is the first temporary molar mandibulaire left.

Anatomy

The teeth are schematically divided into faces.

Face occlusale: it is the face on which one bites. This face consists of cusps (bumps) and pits.
vestibular Face: it is the face being outside, against the cheek.
palatine Face: it is the face inside, in top, finishing towards the palate.
lingual Face: it is the face inside, bellow, that the language effleure usually.
Face proximale or mésiale: it is the hidden side against the tooth just ahead.
distal Face: it is the hidden side against the tooth just behind.

The anatomy of each tooth is single. However certain features return at a more or less high frequency, which can emphasize a " norme" , with always of the individual variations.

incisors:

They have only one root. One distinguishes a vestibular face, a palatine or lingual face, a free edge. The palatine face generally carries a cingulum.

the canines

Teeth with a root, very long. They are at a peak.

the premolars

The premolars lower generally have a root, the first premolar higher has two roots, the second only one. They have two cusps, often very marked.

the molars

The higher molars generally have three roots, the lower molars two. They generally have four cusps, except the first lower molar which has five of them. The wisdom teeth have a more variable anatomy.

Care of the teeth

The teeth being mineral-bearing, they are not very capable of defense reactions. It is particularly important to clean them well, by a regular and adapted brushing.

In the event of pathology, it is necessary to consult a dentist. Dentistry can be subdivided in several parts:

preserving Odontology: one looks after the teeth and reconstitutes them.
Endodontics: it is the field of the interior of the tooth (the pulp).
Prosthesis: allows to reconstitute the too dilapidated teeth, or to replace missing teeth.
Parodontie : care of the Parodonte, i.e. fabrics surrounding the tooth: Gum, alveolar Os.
Surgery: avulsion (extraction) of teeth wisdom or Canine S included or wedged or any dental body too dilapidated to be restored.
Implantologie : it is possible to replace a missing tooth by an implant (or " fixture") and a crown fixed above.
Pédodontie : they is the care of the teeth of the Enfant S.
Orthodontie: treatment of the alignment of the teeth.
Occlusodontie : treatment of the dental, pains, crackings of the Articulation temporo-mandibulaire and the tensions on the level of the muscles masticateurs and cervical problems of contacts.

Dental anomalies

The dental anomalies are very variable because the odontogenèse lasts a long time (several years) and is very sensitive to the various aggressions. In addition certain anomalies are hereditary.

Anomalies of number

Reduction

Hypodontie: miss certain teeth following Agénésie hereditary S. Origine. Rare in temporary teeth.
Oligodontie: absence of many teeth; often the few teeth present are smaller. Often associated with an ectodermal syndrome (Syndrome of Christ-Siemens-Touraine).
Anodontie: no tooth is formed.

Increase: Hyperdontie = polydontie: supernumerary, too many teeth (rarer than hypodontie)

Mésiodens: additional tooth enters the two central incisors jawbones.
Unfolding = twin teeth = supernumerary doubled bloom: either a fourth molar, or a third premolar. These teeth remain generally included.
Hyperdontie syndromique : in the cléïdo-cranial dysostose or the syndrome of Garner.

Polyphilodontie. Normally the man is diphyodonte: two teeth follow one another. Exceptionally one can see three successive teeth.

pre-déciduelle Teeth: rudimentary tooth without root presents to the birth; will fall during the first néo-native week.
post-permanent Teeth.

Anomalies of size

Microdontie : tooth smaller than the normal. Also called " tooth in grain of riz". Often relate to the higher side incisors or the higher wisdom teeth.
Macrodontie: tooth larger than the normal. Can be related to a hypophyseal Gigantisme.

Dysmorphies anomalies of form

Anomalies of all the tooth

Gémination: the germ divided partly; the tooth is bulkier. (or: a normal tooth is stuck to a supernumerary tooth).
Fusion: union with tissue interpenetration of two Germ S, during their formation.
Unfolding: ultimate stage of the gemination. Implied in the étiopathogénie of the supernumerary teeth.
invaginated Tooth = dens in cogs: there is like one second tooth inside the principal tooth (primarily on the monoradiculées teeth).
Taurodontisme: pulpar room abnormally large; apical furcation.
Dilaceration: a traumatism during the formation of the tooth involved a damage of the germ.

Anomalies of the conical crown

Tooth in grain of rice. Relate to especially the side incisors.
évaginée Tooth = run enamel: left additional gross Cuspide. Tuber of Carabelli, tuber of Bolk, tuber of Leong, cingulum disproportionate. They should be eliminated in the event of embarrassment from the occlusion.

Anomalies of roots

Size: abnormal if the length is lower or equal to that of the crown.
Direction: center more or less bent, in bayonet, twisted… These curves can be due to obstacles during the growth.
Number: variable, especially on the third molar: from one to seven roots.
Concrescence = concretion: the roots of two teeth came into contact during the development and amalgamated.

Dystopies

Inclusion: the tooth remains included in the bone without making its eruption.

usual Inclusions: wisdom tooth, canine jawbones, second premolar jawbone.
Inclusion with ectopia or malposition: wisdom tooth in the rising branch of the mandible; tooth in the sine jawbone.

Enclavement and ankylosis: a temporary Dent which does not fall prevents the permanent Dent from pushing.
Ectopia: palatine higher canine; lower side incisor close to the second molar lactéale; wisdom tooth can leave on the level the edge basilaire, under the condyle mandibulaire…
Transposition: inversion of place between two teeth.

Dysplasies anomalies of structure

Dysplasies of general cause

simple Hypoplasie: light modification of the morphology of enamel, without deterioration of the tooth.
complex Hypoplasie: modification of the structure and the general characters of the tooth. Tooth of Hutchinson (central incisor jawbone out of turn of screw); tooth of Mozer (first conical higher molar).
dental Fluorose: defect of mineralization following an excessive ingestion of Fluorine during the formation of the teeth.

Dysplasies of local cause

traumatic Hypoplasie
Hypoplasie of infectious origin: Tooth of Turner

Odontodysplasie regional = phantom tooth. Touch enamel plus the dentine. Rather at the former girls, temporary teeth. They are called thus because one hardly distinguishes them with radiography.
Tooth in scale: had with a stop of growth of the ecto-mésenchymateuse papilla and an incapacity for pulp to form normal dentine.

Dysplasies hereditary

Amélogenèse imperfect: the enamel is not constituted correctly. One distinguishes the imperfect amélogenèses hypoplasic, hypomature, hypomineralized.
Dentinogenèse imperfect: the Dentine is not formed correctly. One distinguishes: type 1: in the imperfect Osteogenesis; type 2: dentine opalescent hereditary; type 3: dentinogenèse imperfect of BrandyWine.

Dyschromies

Dyschromies primitives = intrinsic dyschromies: certain products introduced during the formation of the teeth can color them in the mass. Coloring is final.

Erythrodontie : coloring pink-brown. It is a symptom of the congenital Porphyrie.
green Tooth: had with a néo-native Ictère.
Tooth brown-yellow = coloring with the Tétracycline (an antibiotic).
dental Fluorose: an excessive fluorine contribution can color the teeth. In the moderate forms: fine horizontal and parallel white lines. In the more advanced forms: tasks blanchâtres extending gradually. In the severe forms: yellowish or brownish tasks with deepening reachs. The dental fluorose appears as of regular oral catch of 2 Mg per day of fluorine.
greenish Coloration during treatment by Ciprofloxacine at lez nourissons.

Dyschromies acquired = extrinsic dyschromies: certain products can involve more or less surface colorings of the teeth. Coloring is eliminated by brushing, descaling, polishing or others.

metal Salts: brown Iron, green Copper, black Zinc, money slate.
Chemicals: mercury, tar (in the tobacco), nitrous vapors.
Drugs: Chlorhexidine (brown). The chlorexidine is present in many baths of mouth. Its use with the long course is to be proscribed.
Bacteria: some Bacterium S or mushrooms are chromogenes (green, orange, black).
iatrogenic Causes: a amalgamates can give to the tooth a coloring noirâtre.
Food: coffee, the, wine, bilberries… These colorings are generally reversible.

internal Dyschromies of origin (after eruption of the tooth):

Traumatism: a violent shock causes necroses it pulp, which will involve a brownish coloring or rosâtre of the tooth.
Granulome intern.

Expressions

to make its teeth : to have the teeth which bore, in an young child. By extension it is about a person who learns something by the experiment.
to have a tooth against somebody : to have objections, to be upset with him.
to have the long teeth : to have much ambition.
an eye for an eye and a tooth for a tooth (Law of Retaliation) : by revenge, to inflict with somebody the same damage that it inflicted to you.
to lie like a puller of teeth : to lie without scruple.

Teeth of the animals

See article animal Teeth.

Art and culture

teeth of the sea, film.

See too

tooth|tooth

External bonds

Definition schematized of a tooth
See a detailed diagram of the tooth (cut of a molar)
See diagram of final teeth
anatomical Visions of animal teeth (in English)

Simple: Tooth Zh-min-nan: Chhùi-khí Zh-yue: 牙

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