Hereditary dysplasia (malformation) of the enamel is known as amelogenesis imperfecta (synonyms: Amelogenesis; Amelogenesis imperfecta; Dentine dysplasia; Dentinogenesis imperfecta; Dentinogenesis imperfecta II syndrome; Hereditary tooth structure disorder; Odontogenesis hypoplastica; Odontogenesis imperfecta sive hypoplastica; ICD-10: K00.5). The enamel is impaired in either quantity or quality.The disorder is most common in northern Sweden (1:718), and rather rare in the United States (1:16,000).Amelogenesis imperfecta is classified as follows:
- Hypoplastic type – too little enamel.
- Hypomaturation type – immature enamel.
- Hypocalcification type – under calcified enamel.
- Partial immaturity and under calcification, in combination with taurodontism.
Symptoms – complaints
Both the milk teeth and the permanent teeth are affected:
- Hypersensitivity
- Rough, matte enamel surface
- Glossy, quickly splintering enamel surface
- Discoloration – yellowish-brownish
- Strong attrition of the teeth
- Reduced enamel thickness – punctual or areal.
- Lack of proximal contacts (contact points with adjacent teeth).
- Very soft enamel in hypomaturation type and hypocalcification type.
- Gingivitis (inflammation of the gums)
- Gingival hyperplasia (gum proliferation).
- Frequent frontal open bite
- Loss of vertical jaw relation (bite height)
- Pain
Pathogenesis (disease development) – etiology (causes)
Amelogenesis imperfecta occurs when enamel formation is disrupted. The disease is inherited either autosomal-dominant, autosomal-recessive, or x-linked. Depending on the site at which enamel maturation does not proceed properly, the different forms of AI result. It has been observed that the disease often occurs in combination with one or more of the disorders listed below:
- Eruption disorders of the teeth
- Denticles (hard substance formations occurring in or at the margin of the dental pulp).
- Follicular cysts
- Impacted or retained teeth (teeth completely surrounded by bone) of the second dentition (eruption of teeth from the jaw into the oral cavity).
- Crown and root resorptions
- Taurodontism (dominantly inherited anomaly in which the tooth body is enlarged and the root is shortened).
- Tooth undercount
Consequential diseases
In the context of amelogenesis imperfecta, the enamel wears down very quickly, which can lead to a drop in bite height.
Diagnostics
During the clinical examination, it must be kept in mind that there are many different manifestations of AI. Therefore, a thorough history is important, as it can already be determined whether a hereditary component is present. Radiographically, it can be determined that the density of the enamel in the radiograph is reduced, sometimes dentin-like or even lower. Differential diagnoses to rule out include:
- Acquired enamel formation disorders
- Dentinogenesis imperfecta – autosomal dominant inherited maldevelopment/structural disorder of tooth dentitions that occurs in approximately 1 in 8,000 people and results in severe tooth abrasion.
- Enamel dysplasias in other diseases – amelo-onchohypohidrosis syndrome, epidermolysis bullosa, mucopolysaccharidoses, oculodentodigital syndrome, tricho-dental osteosclerotic syndrome.
Therapy
Because severe, rapid attrition and abrasion occur in the course of amelogenesis imperfecta, early therapeutic intervention is always advisable. Due to severe tooth wear, patients rapidly lose vertical height (bite height). In the deciduous dentition, plastic fillings, strip crowns and steel crowns are the restoration options that are most commonly used. In this way, the teeth are preserved as far as possible until their physiological failure, and the child is enabled to eat and develop speech without interference. In adulthood, various types of crowns (e.g. all-ceramics, zirconium dioxide) are available for restoration in addition to plastic fillings.Here, too, therapy should be carried out before massive damage and discomfort occur in order to relieve patients of the limitations and discomfort associated with the disease as early as possible and to rehabilitate them both esthetically and functionally. It is important to bear in mind that soft enamel, which quickly wears away and turns yellowish-brown, represents a strong psychological burden for patients in addition to local discomfort, as they are significantly limited in their visual appearance.
