Hereditary amelogenesis imperfecta, Lecture notes of Dentistry

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KIUT

DENTISTRY

No. 4.

Hereditary amelogenesis imperfecta.

KIUT

DENTISTRY

Subject : CLINICAL RESTORATIVE DENTISTRY 2 Lecturer : PhD, Associate Professor Khatamov Ulugbek Altibaevich Tashkent 2025

• (^) Hereditary dental tissue developmental

disorders are genetically determined

pathologies affecting the formation of

enamel, dentin, and sometimes

cementum. These disorders can manifest

as a variety of clinical manifestations,

reflecting both quantitative and

qualitative changes in tooth structure.

Main categories of hereditary disorders

• Hereditary amelogenesis imperfecta (HAI) This disease disrupts enamel formation. Clinical manifestations can range from minor defects (reduced tooth size, slight discoloration) to severe enamel thinning with pits, grooves, and shade changes (from yellow to brown). NNA can be inherited in an autosomal dominant, autosomal recessive, or X-linked manner.
• Hereditary dentinogenesis imperfecta (HDI) Disruption of dentin formation leads to a decrease in its mineral content and changes in its structure. This condition can manifest as increased tooth translucency, opalescence (teeth appearing "glassy"), and increased sensitivity to irritants. While caries develops less frequently, teeth are prone to rapid wear.

• Hereditary amelogenesis imperfecta (HAI) is a genetic disorder of dental enamel formation that affects both primary and permanent teeth. The disorder is caused by mutations in genes responsible for enamel synthesis and mineralization (e.g., AMELX, ENAM, KLK4, MMP-20, and DLX3), which lead to disruptions at various stages of enamel formation. The disorder can be inherited in an autosomal dominant, autosomal recessive, or X-linked manner.
• Amelogenesis imperfecta is a genetic disorder of tooth enamel formation that results in structural defects, discoloration, increased sensitivity, and a tendency to decay. This condition can affect both primary and permanent teeth and is often accompanied by aesthetic and functional problems.

Amelogenesis

Amelogenesis imperfecta

Clinical manifestations of NNA are varied and depend on the nature of the enamel apparatus disorder:

• (^) Hypoplastic form: a decrease in the amount of enamel matrix is observed , leading to thinning of the enamel, the appearance of pits, grooves, and a decrease in the size of the teeth. While the teeth may be normally shaped, gaps often form between them.
• (^) Hypomaturation form: the thickness of the enamel is preserved, but its maturation is disrupted , as a result of which the enamel becomes less strong , acquires a matte or altered shade (from light white to dark brown) and tooth sensitivity increases.
• (^) Hypocalcification form: enamel is formed with normal thickness, but its mineralization is impaired with insufficient calcium content. As a result, the enamel becomes soft, prone to chipping and rapid wear. Combined variants also occur (for example, hypomaturation with hypoplasia and taurodontism ), which further complicates the clinical picture.

Clinical picture

• Clinical manifestations:

After eruption, the enamel takes on a yellowish and

brownish tint. Microscopically, unevenness of the

enamel-dentin junction and an increase in the amount of

organic matter are revealed.

One to three years after eruption, the enamel becomes

matte, rough, and cracks appear; the color changes to

brown. Dentin is dense and brown.

At the moment of eruption, the enamel is white,

covered with grooves, and quickly disappears, revealing

the dark brown dentin of normal structure.

At the moment of eruption, the enamel is

chalky , matte, absent in places and easily

separated from the dentin under mechanical action.

Patients complain of increased tooth

sensitivity.

Microscopically, dentin has a normal structure,

while the remaining enamel is significantly altered:

the orientation of the prisms is disrupted,

their transverse striations are increased , and

prism-free zones filled with an amorphous

substance are found.