Amelogenesis Imperfectaa

Developmental Alterations of Teeth II

Amelogenesis Imperfecta pp: 99-106

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General Information
• Classification can be impractical for clinicians • Problems arise in one or more of the three stages of enamel formation
– Elaboration of enamel matrix; hypoplastic – Mineralization; hypocalcified – Maturation; hypomaturation

General Information
• • • • • • • • • Absence of systemic disorder Can be part of a syndrome Many types Different modes of inheritance Different phenotypes in a single family Same phenotype with different gene mutations Homozygotes differ from heterozygotes 1:800 – 1:15,000 (clustering) Both dentitions

Genes and Phenotypes
• AMELX (amelogenin)
– X-linked – Diffuse smooth hypoplastic and hypomaturation

Hypoplastic type
• • • • Inadequate deposition of organic matrix Normal mineralization Radiographic contrast Seven types

• ENAM (enamelin)
– AD, AR – Generalized pitting and thin enamel

• MMP-20 (enamelysin)
– AR pigmented hypomaturation

• KLK4 (kallikrein-4)
– hypomaturation

• DLX3 (genes of craniofacial development)
– Hypoplastic/hypomaturation and taurodontism

• AMBN (ameloblastin)
– Indication for strong association

1

Hypoplastic type
Generalized Pitted
• • • • • • A.D. Pinpoint/head pits in rows or columns In-between enamel normal Across the surface Buccal surface more severely affected Does not correlate with pattern of environmental damage

Hypoplastic type
Generalized Pitted

Hypoplastic type
Generalized Pitted

Hypoplastic type
Generalized Pitted

Hypoplastic type
Generalized Pitted

2

Hypoplastic type
Localized Pitted
• • • • • • • A.D. or A.R. (more severe) Pinpoint/head pits in rows Linear depression or area of hypoplasia Middle third of buccal surface Incisal or occlusal unaffected All teeth or some teeth Primary