Amelogenesis Imperfecta Classification — MFDS Part 1 MCQ

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ModerateOral PathologyAmelogenesis Imperfecta ClassificationMFDS Part 1

A patient with generalised amelogenesis imperfecta has enamel that is reduced in thickness but remains relatively well mineralised and hard. Which principal phenotype is this?

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Correct answer: B — Hypoplastic type

The correct answer is B, the hypoplastic type. This is primarily a quantitative defect of enamel-matrix formation: the enamel is reduced in thickness but is relatively well mineralised and therefore remains hard. In hypocalcified amelogenesis imperfecta, enamel thickness is initially near normal, but mineralisation is markedly defective, making the enamel soft and susceptible to rapid loss. Hypomaturation enamel is also generally near normal in thickness but has impaired final maturation, reduced hardness and an opaque appearance. The hypoplastic-hypomaturation type combines quantitative and maturation defects and is associated with taurodontism. Snow-capped amelogenesis imperfecta is a hypomaturation phenotype rather than a purely hypoplastic defect.

Reference: Wright JT, Robinson C, Shore R. Characterization of the enamel ultrastructure and mineral content in hypoplastic amelogenesis imperfecta. Oral Surgery, Oral Medicine, and Oral Pathology. 1991;72(5):594–601. https://pubmed.ncbi.nlm.nih.gov/1745518/