What Is Anodontia?

Congenitally absent teeth are also known as insufficient teeth. It refers to the congenital anomalies that have not developed and formed teeth during the formation of tooth germ, or early in the development of tooth germ, that is, the period of tooth bud formation.

Congenital missing teeth

Congenitally absent teeth are also known as insufficient teeth. It refers to the congenital anomalies that have not developed and formed teeth during the formation of tooth germ, or early in the development of tooth germ, that is, the period of tooth bud formation.

Overview of Congenital Missing Teeth

Classification of congenital missing teeth

Congenital missing teeth can be divided into individual missing teeth (hypodontia), most missing teeth (oligogontia) and congenital anodontia (anodontia).

Individual tooth loss The congenital individual tooth loss is usually not accompanied by abnormal development of other tissues and organs throughout the body.

Part of the tooth is missing and many teeth are congenital.

Congenital odontosis refers to a serious manifestation of congenital loss of most teeth, most of which are completely toothless.

Congenital missing individual or partial tooth

Cause

The etiology of individual tooth loss has not yet been clarified, and may be related to insufficient dental plate formation or inhibition of tooth germ proliferation. Some scholars believe that it is related to heredity, and some believe that it is the result of early embryos affected by harmful substances. For example, exposure to X-rays in the early stages of tooth germ development can cause local tooth loss. Most congenital missing teeth are related to genetic factors. Grahnen (1956) surveyed the parents of 171 children with congenital tooth loss, and found that if one of the parents had congenital tooth loss, the child's rate of congenital tooth loss was high, and congenital tooth loss was considered to be an autosomal dominant genetic disease. . The investigation found that the congenital missing tooth had no obvious relationship with other factors, such as the age of the parents, the health status of the mother during pregnancy, the health status from birth to 1 year old, parity, and socioeconomic status of the family.

1. Genetic factors: Generally have a very obvious family history, parents or grandparents in the family have missing teeth;

2. Metabolic disorders: Maternal pregnancy diseases or metabolic disorders cause breast / permanent tooth developmental defects;

3. Nutritional disorders: Nutritional disorders such as calcium, iron, and protein deficiency in the mother's body during the early stages of tooth germ development.

4. Endocrine disorders: Maternal endocrine disorders in the early stages of tooth germ development can also lead to congenital tooth loss.

5. Ray effects: If the tooth germ is exposed to X-rays in the early stage of development, the teeth on the side of the irradiation may be missing.

6, infection factors: some pathogenic microorganisms such as rubella virus, Treponema pallidum infection and so on.

7, hereditary diseases: most of the missing teeth and total mouth loss are often related to genetic diseases such as hereditary ectodermal hypoplasia, is a systemic congenital malformation, lack of sebaceous and sweat glands, dry skin, less or no sweat And thinning hair, collapsed bridge of the nose, partial or complete loss of teeth.

8. Systemic diseases: Systemic systemic diseases such as tuberculosis and rickets can cause embryo destruction or block development of teeth, and may also cause congenital missing teeth.

Clinical manifestation

1. Missing teeth in the mouth, the number and location of missing teeth are different.

2. Congenital missing teeth can occur in deciduous teeth and permanent teeth. Permanent teeth are more common than deciduous teeth.

3. There are obvious racial differences. The incidence of Eskimos, Indians and Orientals is higher, and the incidence of blacks is lower.

4. The male to female ratio is 2: 3.

5. Any tooth in the permanent dentition may have congenital loss, the most common is the third molar, followed by the mandibular second premolar, 6. maxillary lateral incisor and maxillary second premolar. Least missing is the first molar, followed by the second molar.

7. Most patients with missing molars are accompanied by the loss of other teeth, and fewer are missing molars alone.

8. Missing teeth can occur on one or both sides.

9. The missing teeth are mostly symmetrically distributed.

10. The number of missing teeth is the most common, followed by one, and the number of missing teeth is the least common.

treatment

The principle of treatment of congenital tooth loss is to restore chewing function and maintain good jaw relationship.

1. When the number of missing teeth is small, it has little effect on chewing function, dentition shape and aesthetics, so it can be left untreated.

2. Most congenital missing teeth not only affect the chewing function, but also affect the appearance of the patient, causing physical and psychological damage to the patient. Therefore, when the number of missing teeth is large, it can be used to repair active dentures, restore chewing function, and promote the development of maxillofacial bones and muscles. However, the restoration must be constantly updated with the growth and development of children. It is usually replaced once a year to avoid hindering the development of children's jaws.

3. When the maxillary lateral incisor is missing, after analyzing the jaw relationship, a gap retainer or an occlusal induction method can be used to move the permanent canine to the lateral incisor position, and then adjust and reshape the canine crown to replace the lateral incisor .

4. When permanent teeth are congenitally missing, the preservation or extraction of deciduous teeth is often a clinical issue worth considering. When the permanent dentition is crowded, the deciduous teeth that lack the inherited permanent teeth can be removed to provide clearance for the crowded permanent teeth. When the permanent teeth are arranged loosely and with gaps, the retained deciduous teeth can be retained to maintain the complete dentition and chewing function. The retention time of deciduous teeth varies greatly from individual to individual. After the retained deciduous teeth are detached, repair treatment is performed.

Congenital toothlessness

Cause

Ectodermal dysplasia syndrome (ectodermal dysplamasyndrome) is a more common type of hereditary diseases in the stomatology department, which manifests as a variety of syndromes such as congenital loss of teeth, thinning hair and abnormal skin.

Clouston (1939) classified the disease into two categories, one is sweatless ectodermal hypoplasia, and the other is sweaty ectodermal hypoplasia. Anhidrotm type patients have no sweat glands or sparse glands in their skin, so they have trouble regulating their body temperature. In patients with sweat type (hidrotlc type), sweat glands are normal, but the structure of teeth, hair, and skin is abnormal.

This disease is a hereditary disease, and the genetic method has not been fully understood. Most cases are associated with X recessive inheritance, and can also be autosomal dominant or recessive inheritance. More men than women. Different ectodermal hypoplasia syndromes have different genetic patterns.

Ectodermal hypoplasia is within or within families, with clinical heterogeneity. Erelve et al. Pointed out that ectodermal hypoplasia has 117 variants, and the clinical phenotype is not necessarily a characterization of genotypes, and several genes may show a phenotype. Similar or even the same disease may have different etiology or different genetic mechanisms. This phenomenon is called genetic heterogeneity.

Due to the congenital abnormalities of the ectoderm and its appendages, some or all sweat glands are missing, and because the tooth plate of the ectoderm is underdeveloped or underdeveloped, lacking the starting base of the teeth, and cannot induce the development of mesenchymal odontoblasts, and Causes partial or full edentulous deformity.

Clinical manifestation

The main manifestation of non-sweat type ectodermal hypoplasia is the absence or absence of sweat glands in children, no sweating or little sweating, and high temperature tolerance. Therefore, when the temperature slightly increases, or when exercise or mild infection occurs , That is, there is obvious discomfort or high fever, young children often see a doctor for fever of unknown reason; children lack hair follicles and sebaceous glands, dry skin and more wrinkles, especially the skin around the eyes; hair, eyebrows, sweaty hair is dry; refers to ( Toe) dysplasia; the child has stunted physical growth, short stature, bulging forehead and upper orbit and nasal depression, protruding lips and prominent auricles. Sexual development is normal, 30% to 50% of children with poor intelligence.

The most prominent manifestation in the oral cavity is congenital missing teeth, deciduous teeth and permanent teeth are often missing, or there are only a few teeth. The remaining tooth gap is widened, the distance is sparse, and the tooth shape is small and conical. There is no alveolar ridge in the toothless area, but jaw development is not affected. Some salivary glands are stunted, have less saliva, and have a dry mouth. Parents often seek consultations because the child does not have teeth.

Sweat-type ectodermal hypoplasia, also known as hair-nail-dental-tooth syndrome (trichoarycho-dental-syndrome), is mainly manifested in the normal development of sweat glands in children, and other manifestations are similar to those of sweat-free ectoderms, such as hair and eyebrow Slender, light-colored, sparse, sluggish nails, thin and fragile, with streaks and particularly shiny, often nail groove infections can cause the finger (toe) methylation to disintegrate, or the nails are missing or thickened. Oral manifestations also include congenital missing teeth, varying numbers of missing teeth, or abnormal morphological development. The anterior teeth are mostly tapered teeth, or the enamel is poorly developed, the enamel is thin, the horizontal stripes are obvious, or small pits appear.

treatment

In order to restore chewing function and promote the development of jaws and muscles, it can be used as an active denture restoration. The restoration must be continuously replaced with the growth and development of the occlusion and the age of the child. ^[1]