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Table 1 Classification systems applied to amelogenesis imperfecta

From: 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)