Diagnostic study of number anomalies (by excess and defect)
Introduction :
The orthodontist is faced with different types of anomalies which have more or less serious repercussions on the function and aesthetics of the patient; the treatment of these will depend on their location, their origin and their type.
Definition :
GYSEL: “dental anomaly is any alteration of the external appearance, internal structure or topography of one or more teeth, resulting from any disorder occurring during the development of the dentition”
Exogenous: trauma, taking medications that disrupt the mineralization of the hard tissues of the tooth, premature extraction of temporary teeth.
Anomalies can be distinguished:
- Eruption anomalies:
-Delay
-Advance
- Situation anomalies:
-Transposition.
– Ectopia.
-Inclusion.
-Dystopias.
- Number anomalies:
-By excess: additional teeth supernumerary teeth multiple excesses
-Default: agenesis, oligodontia or anodontia.
- Shape anomalies:
-Morphology.
-Size.
- Structural anomalies.
Eruption anomalies:
We speak of eruption anomalies when this physiological event occurs well below or well beyond the usually accepted age limits with a chronological gap of several months or even several years.
Etiologies:
Baby teeth:
-Superficial position of the germ
-Hormonal disorders: hyperthyroidism
– Expulsive folliculitis: inflammation of the dental follicle can cause the expulsion of a developing tooth, without a root .
In permanent teeth :
The early eruption of all permanent teeth is linked to certain endocrine hyperfunctions, precocious puberty, hyperthyroidism or even premature exfoliation of permanent teeth.
Delayed eruption:
General causes:
-Hereditary factors
-Endocrine factors : hypothyroidism.
In permanent teeth :
Delayed eruption can affect a single tooth, in which case it is of local etiology and is the most frequent, but it can also affect a group of teeth or the entire dentition, in which case their causes are systemic or genetic.
Situation anomalies:
Transposition:
Transposition is often defined as an exceptional dental phenomenon in which two adjacent teeth in the dental arch exchange their position.
Ectopia:
This is the situation in which the tooth erupts in a site more or less distant from normal.
Inclusion:
An impacted tooth is a tooth that has completed its root formation but whose follicular sac does not communicate with the oral cavity. A distinction is made between impacted teeth and retained teeth.
On X-ray examination:
-Panoramic radiography allows the inclusion to be detected and the degree of rhizalysis of the homologous temporary tooth to be estimated.
Dystopias:
This term refers to the misposition of the tooth in relation to its normal location on the arch, the curve of the arch serves as a reference line. We distinguish:
The version: inclination of the major axis of the tooth, it can be coronal, radicular or mixed.
Aggression: indicates the movement of the tooth in its entirety parallel to its major axis, it is a translation movement.
Rotation: the tooth moves around a vertical axis, we describe 2 types of rotation:
Marginal rotation: when one edge moves and the other stays in place
Axial rotation: when both edges move, one in one direction and the other in the opposite direction.
Number anomalies:
The dental formula in humans is stable, it includes 20 deciduous teeth and 32 permanent teeth, the number of teeth can vary, most often in the direction of a decrease, the reduction of one or two elements is a common observation, more exceptional is the absence of several units, or even almost all the teeth.
a)- By excess
Extra teeth: teeth with a harmonious shape and volume approximately identical to the usual tooth.
Supernumerary teeth: A supernumerary tooth is a number anomaly that is more common in permanent dentition than in temporary dentition. It is most often located in the incisor region of the upper jaw.
The supernumerary tooth has a wide variety of forms. It can manifest itself in different ways: from the most obvious (tooth on the arch) to the least suspected (impacted tooth). Very often, it will be the subject of a fortuitous discovery on X-ray.
Odontologist:
Mesiodens: is an additional or supernumerary tooth that develops between the two central incisors of the upper jaw.
b)- By default:
Agenesis: corresponding to the absence of a dental unit in relation to the absence of the corresponding germ.
Missing teeth can disrupt the alignment of adjacent teeth and lead to orthodontic problems such as excessive spaces.
Agenesis can make these functions more difficult and lead to problems with nutrition and speech.
Missing teeth can impact the aesthetic appearance of your smile.
Oligodontia: is a rare abnormality of dental development in humans, characterized by the absence of six or more teeth. It can be isolated or associated with other malformations or syndromes. It can have genetic, environmental or unknown causes
Anodontia: is a rare anomaly of dental development, characterized by the complete absence of all teeth, temporary or permanent. It is often associated with syndromes of genetic origin, such as ectodermal dysplasias, which affect the skin, hair, nails and sweat glands. Anodontia can lead to functional, aesthetic and psychological problems, and requires the installation of adapted dental prostheses1
Morphological anomalies:
Microdontia: this indicates a reduction in the volume of the teeth.
Upper lateral microdontia accompanies cleft lip and alveolar cleft (often with delayed eruption and agenesis) and is part of several syndromes.
Macrodontia: characterized by dental gigantism, can be localized to a single or a group of teeth.
* Fusion: coalescence of two dental germs by their crown
* Gemination: coalescence of all the tissues of two teeth
* Concrescence: union of two or more roots of different teeth.
Various forms:
*Taurodontia: more apical furcation, frequent in subjects with chromosomal abnormalities (trisomy 21)
* Dens in dente: there is a second tooth inside the main tooth
* Odontomas
Structural anomalies:
Enamel damage:
All forms of enamel hypoplasia are observed on the upper central incisors. The germs of these teeth are in fact, with those of the first molars, the sites where the mineralization of the enamel and dentine matrices begins.
a) Simple partial hypoplasia:
They are the consequence of disorders of the mineralization of the adamentine matrix during a relatively limited period.
These hypoplasias can be:
* cup-shaped: small, roughly punctiform depressions * linear or furrow-shaped: in the form of a fine furrow of variable depth * in sheets b) Complex partial hypoplasias: They are accompanied by significant changes in the coronal morphology c) Generalized hypoplasias: This is amelogenesis imperfecta or brown hypoplasia of the enamel. It is characterized by a defect in the enamel that can affect all the teeth of one or both sets of teeth. Dentin damage. They are characterized by dentinogenesis imperfecta or dentinogenesis imperfecta, or hereditary opalescent dentin = GARDERONT dysplasia Color anomalies or dyschromias: According to MUGNIER, “Any dental crown whose color deviates from its usual whiteness presents dyschromia”. a) Dyschromias of genetic origin * Porphyria which manifests itself by other signs (urinary, cutaneous and ocular) gives temporary or permanent teeth of pinkish tint. * Neonatal jaundice.
b) Acquired dyschromia:
c) Pathological dyschromia:
They result from dental caries and accompany all its stages, ranging from a simple chalky whitish spot or leucoma or “alarm dyschromia” for MUGNIER to the entire range of grays.
Traumatic dyschromia (also pathological):
They lead to changes in the color of the permanent incisors following trauma.
c) Drug-induced dyschromia:
* Fluorosis or DARMOUS is observed in subjects who were born and have lived during their early childhood (up to 8 years) in regions where drinking water contains a natural fluoride content greater than 1.5 mg/liter.
It is a disease that weakens tooth enamel and makes them very sensitive.
Conclusion :
We have just seen the diversity of anomalies that can be encountered in orthodontics , the orthodontist must know them perfectly.
Their signs, whether clinical or radiological, their causes as well as their consequences, because the early diagnosis of these anomalies will allow the initiation of interceptive treatments which will have the advantages of either eliminating active treatment in permanent teeth, or reducing the duration of treatment, or even allowing a reduction in the incidence of extractions.
Diagnostic study of number anomalies (by excess and defect)
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