AMELOGENESIS IMPERFECTA

CLASSIFICAION OF AMELOGENESIS IMPERFECTA

Weinmann et al., 1945 [4] Two types based solely on phenotype: hypoplastic and hypocalcified

Darling, 1956 [5] Five phenotypes based on clinical, microradiographic and histopathological findings.
Hypoplastic
Group 1 – generalised pitting
Group2 – vertical grooves (now known to be X-linked AI)
Group 3 – Generalised hypoplasia
Hypocalcified
Type 4A – chalky, yellow, brown enamel
Type 4B – marked enamel discolouration and softness with post-eruptive loss of enamel
Type 5 – generalised or localised discolouration and chipping of enamel

Witkop, 1957 [6] Classification based primarily on phenotype. 5 types:
1. Hypoplastic
2. Hypocalcification
3. Hypomaturation
4. Pigmented hypomaturation
5. Local hypoplasia
Added mode of inheritance as further means of delineating cases.

Schulze, 1970 [7] Classification based on phenotype and mode of inheritance.

Witkop and Rao, 1971 [8] Classification based on phenotype and mode of inheritance. Three broad categories: hypoplastic, hypocalcificied,
hypomaturation.
a. Hypoplastic
Autosomal dominant hypoplastic-hypomaturation with taurodontism (subdivded into a and b according to author)
Autosomal dominant smooth hypoplastic with eruption defect and resorption of teeth
Autosomal dominant rough hypoplastic
Autosomal dominant pitted hypoplastic
Autosomal dominant local hypoplastic
X-linked dominant rough hypoplastic
b. Hypocalcified
Autosomal dominant hypocalcified
c. Hypomaturation
X-linked recessive hypomaturation
Autosomal recessive pigmented hypomaturation
Autosomal dominant snow-capped teeth
White hypomature spots

Winter and Brook, 1975 [9] Classification based primarily on phenotype. Four main categories: hypoplasia, hypocalcification, hypomaturation,
hypomaturation-hypoplasia with taurodontism, with mode of inheritance as a secondary means of sub-classification.
a. Hypoplasia
Type I. Autosomal dominant thin and smooth hypoplasia with eruption defect and resorption of teeth
Type II. Autosomal dominant thin and rough hypoplasia
Type III. Autosomal dominant randomly pitted hypoplasia
Type IV. Autosomal dominant localised hypoplasia
Type V. X-linked dominant rough hypoplasia
b. Hypocalcification
Autosomal dominant hypocalcification
c. Hypomaturation
Type I. X-linked recessive hypomaturation
Type II. Autosomal recessive pigmented hypomaturation
Type III. Snow-capped teeth
d. Hypomaturation-hypoplasia with taurodontism
Type I. Autosomal dominant smooth hypomaturation with occasional hypoplastic pits and taurodontism
Type II. Autosomal dominant smooth hypomaturation with thin hypoplasia and taurodontism

Witkop and Sauk, 1976 [2] Classification based on phenotype and mode of inheritance, similar to classification of Witkop and Rao (1971)

Sundell and Koch, 1985 [10] Classification based solely on phenotype

Witkop, 1988 [11] Four major categories based primarily on phenotype (hypoplastic, hypomaturation, hypocalcified, hypomaturation-hypoplastic
with taurodontism) subdivided into 15 subtypes by phenotype and and secondarily by mode of inheritance.
Type I. Hypoplastic
Type IA. Hypoplastic, pitted autosomal dominant
Type IB. Hypoplastic, local autosomal dominant
Type IC. Hypoplastic, local autosomal recessive
Type ID. Hypoplastic, smooth autosomal dominant
Type IE. Hypoplastic, smooth X-linked dominant
Type IF. Hypoplastic, rough autosomal dominant
Type IG. Enamel agenesis, autosomal recessive
Type II. Hypomaturation
Type IIA. Hypomaturation, pigmented autosomal recessive
Type IIB. Hypomaturation, X-linked recessive
Type IIC. Hypomaturation, snow-capped teeth, X-linked
Type IID. Hypomaturation, snow-capped teeth, autosomal dominant?
Type IIIA. Autosomal dominant
Type IIIB. Autosomal recessive
Type IV. Hypomaturation-hypoplastic with taurodontism
Type IVA. Hypomaturation-hypoplastic with taurodontism, autosomal dominant
Type IVB. Hypoplastic-hypomaturation with taurodontism, autosomal dominant

Aldred and Crawford, 1995[12]
Classification based on:
Molecular defect (when known)
Biochemical result (when known)
Mode of inheritance
Phenotype

Hart et al., 2002 [13] Proposed a molecular defect sub classification of the AMELX conditions
1.1 Genomic DNA sequence
1.2 cDNA sequence
1.3 Amino acid sequence
1.4 Nucleotide and amino-acid sequences
1.5 AMELX mutations described to date

Aldred et al., 2003 [1] Classification based on:
Mode of inheritance
Phenotype – Clinical and Radiographic
Molecular defect (when known)
Biochemical result (when known)

Orphanet Journal of Rare Diseases 2007