Amelogenesis imperfecta

Genetic disorder resulting in abnormal enamel

Amelogenesis imperfecta
Synonyms	Hereditary enamel dysplasia
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Field	Dentistry, Genetic disorders
Symptoms	Enamel hypoplasia, tooth discoloration, tooth sensitivity, rapid tooth wear, malocclusion
Complications	Increased risk of dental caries, tooth fractures, psychosocial impact
Onset	Congenital (present at birth)
Duration	Lifelong
Types	Hypoplastic, hypocalcified, hypomaturation, and mixed types
Causes	Mutations in genes such as ENAM, AMELX, MMP20, FAM83H, KLK4
Risks	Autosomal dominant, autosomal recessive, or X-linked inheritance patterns
Diagnosis	Clinical examination, family history, genetic testing, radiography
Differential diagnosis	Dentinogenesis imperfecta, fluorosis, enamel hypoplasia due to systemic causes
Prevention	Genetic counseling for affected families
Treatment	Restorative dentistry, crowns, veneers, orthodontics
Medication	Not applicable
Prognosis	Variable; manageable with dental care
Frequency	Rare (1 in 700 to 1 in 14,000)
Deaths	None (non-lethal condition)

Amelogenesis imperfecta is a genetic disorder that affects the development of tooth enamel, the hard outer layer of the teeth. This condition results in enamel that is abnormally thin, soft, or improperly formed, leading to teeth that are discolored, sensitive, and prone to damage.

Classification

Amelogenesis imperfecta is classified into several types based on the specific enamel defects and the genetic mutations involved. The main types include:

• Hypoplastic type: Characterized by insufficient enamel formation, leading to thin enamel. Teeth may appear small and have pits or grooves.
• Hypomaturation type: Enamel is of normal thickness but is softer than normal. Teeth may appear mottled and have a chalky texture.
• Hypocalcified type: Enamel is of normal thickness but poorly mineralized, making it soft and easily worn away. Teeth often appear yellow-brown and are prone to rapid wear.

Genetics

Amelogenesis imperfecta is caused by mutations in genes that are critical for enamel formation. These genes include:

• AMELX: Located on the X chromosome, mutations in this gene can lead to X-linked amelogenesis imperfecta.
• ENAM: Mutations in this gene can cause autosomal dominant or recessive forms of the condition.
• MMP20: This gene is involved in the maturation of enamel, and mutations can lead to enamel defects.
• KLK4: Mutations in this gene affect the final stages of enamel maturation.

Clinical Features

The clinical presentation of amelogenesis imperfecta can vary widely, but common features include:

• Discolored teeth, often yellow, brown, or gray.
• Increased tooth sensitivity to temperature changes and mechanical forces.
• Rapid wear and breakage of teeth due to soft enamel.
• Malocclusion and altered dental occlusion due to enamel defects.

Diagnosis

Diagnosis of amelogenesis imperfecta is based on clinical examination, family history, and genetic testing. Dental X-rays can help assess the thickness and density of enamel. Genetic testing can identify specific mutations responsible for the condition.

Management

Management of amelogenesis imperfecta focuses on protecting the teeth and improving their appearance. Treatment options include:

• Dental crowns and veneers to protect and restore the appearance of affected teeth.
• Bonding agents to strengthen enamel and reduce sensitivity.
• Regular dental check-ups to monitor and manage dental health.

Prognosis

The prognosis for individuals with amelogenesis imperfecta varies depending on the severity of the condition and the effectiveness of dental management. With appropriate care, individuals can maintain functional and aesthetically pleasing dentition.

Related pages

• Tooth enamel
• Genetic disorder
• Dental restoration