Most often of genetic origin, dental agenesis is characterized by the absence of formation of one or more teeth. More or less severe, it sometimes has important functional and aesthetic repercussions, with a significant psychological impact. The orthodontic check-up allows us to estimate if braces or dental implants can be beneficial.
What is dental agenesis?
Dental agenesis is characterized by the absence of one or more teeth, because they have not formed. This anomaly can affect milk teeth (children without teeth) but much more often affects permanent teeth.
There are moderate and severe forms of dental agenesis:
- When only a few teeth are affected, it is called hypodontia (one to six missing teeth).
- Oligodontia refers to the absence of more than six teeth. Often accompanied by malformations affecting other organs, it can be associated with different syndromes.
- Finally, anodontia refers to the total absence of teeth, which is also accompanied by other organ anomalies.
Dental agenesis is most often congenital. In the vast majority of cases, it is of genetic origin (hereditary genetic anomaly or sporadic appearance in the individual), but environmental factors are also likely to be involved.
Different mutations targeting genes involved in tooth formation may be involved.
- Isolated dental agenesis is when the genetic defect affects only the development of the teeth.
- Syndromic dental agenesis is related to genetic abnormalities that also affect the development of other tissues. The absence of teeth is often the first symptom. There are about 150 of these syndromes: ectodermal dysplasia, Down syndrome, Van der Woude syndrome, etc.
The exposure of the fetus to certain environmental factors affects the formation of dental germs. These may be physical (ionizing radiation) or chemical (drugs taken by the mother), but also maternal infectious diseases (syphilis, tuberculosis, rubella…).
Treatment of pediatric cancer by chemotherapy or radiotherapy can cause multiple agenesis, more or less severe depending on the age of the treatment and the doses administered.
Finally, major craniofacial trauma may be responsible for dental agenesis.
Clinical examination and panoramic radiography are the mainstays of diagnosis. A retroalveolar radiograph – the classic intraoral radiograph commonly performed in the dental office – is sometimes performed.
Patients suffering from oligodontia are referred to a specialized consultation, which will offer a complete diagnostic workup and coordinate multidisciplinary management.
An orthodontic assessment is essential in cases of oligodontia. It is based on skull profile teleradiography, cone beam (CBCT), a high-resolution X-ray technique that allows 3D digital reconstructions, exo- and endobuccal photographs and orthodontic casts.
Genetic counseling will help determine whether or not the oligodontia is syndromic and discuss hereditary issues.
The people concerned
Tooth agenesis is one of the most common dental anomalies in humans, but in the vast majority of cases only one or two teeth are missing. Agenesis of the wisdom teeth is the most common, affecting up to 20-30% of the population.
Oligodonty, on the other hand, is considered a rare condition (frequency of less than 0.1% in various studies). The total absence of teeth is
Overall, women are more frequently affected than men, but this trend seems to be reversed if only the forms with the largest number of missing teeth are considered.
The frequency of agenesis as well as the type of missing teeth also varies according to ethnicity. Thus, Caucasian Europeans are less affected than Chinese.
Symptoms of dental agenesis
In mild forms (hypodontia), the wisdom teeth are most often missing. The lateral incisors and premolars are also likely to be missing.
In more severe forms (oligodontia), the canines, first and second molars or upper central incisors may also be involved. When oligodontia affects permanent teeth, the deciduous teeth may persist beyond the normal age.
Oligodontia can be accompanied by various abnormalities affecting the other teeth and the jaw such as
- Smaller teeth,
- conical or abnormally shaped teeth
- enamel defects,
- happiness teeth,
- late eruption,
- alveolar bone hypotrophy.
Associated syndromic anomalies
Tooth agenesis is associated with cleft lip and palate in certain syndromes such as Van der Woude syndrome.
Oligodontia can also be associated with a deficit of salivary secretion, hair or nail anomalies, dysfunction of the sweat glands…
Disorders related to multiple agenesis
Multiple dental agenesis can lead to insufficient jaw growth (hypoplasia). The bone is not stimulated by chewing and tends to melt.
In addition, a poor occlusion (malocclusion) of the oral cavity can have serious functional consequences. Affected children frequently suffer from chewing and swallowing disorders, which can lead to chronic digestive problems, with an impact on growth and health. Phonation is also affected, and language delays cannot be excluded. Ventilation problems are sometimes present.
The consequences on the quality of life are not negligible. The aesthetic impact of multiple agenesis is often unpleasant. As children grow older, they tend to isolate themselves and avoid laughing, smiling or eating in the presence of others. Without treatment, self-esteem and social life tend to deteriorate.
Treatments for dental agenesis
The treatment aims to preserve the remaining dental capital, to restore a good occlusion of the oral cavity and to improve aesthetics. Depending on the number and location of the missing teeth, rehabilitation may involve prostheses or dental implants.
Oligodontia requires a long-term treatment with several interventions as the patient grows.
Orthodontic treatment allows, if necessary, to modify the alignment and positioning of the remaining teeth. It can be used to close the space between two teeth or to enlarge it before replacing the missing tooth.
Prosthetic rehabilitation can begin before the age of two. It involves removable partial dentures or fixed prostheses (veneers, crowns or bridges).
When feasible, dental implants offer a long-lasting solution. They often require a bone graft beforehand. The placement of 2 (or even 4) implants before the end of growth is only possible in the mandibular anterior region (lower jaw). The other types of implants are placed after the end of growth.
The dentist may have to treat associated dental anomalies. Composite resins are used to restore the natural appearance of the teeth.
Follow-up by a psychologist can be beneficial to help the child overcome difficulties.
Preventing dental agenesis
There is no way to prevent dental agenesis. However, the protection of the remaining teeth is important, especially if enamel defects put the risk of caries high, and oral hygiene education plays an essential role.