From: Amelogenesis imperfecta
Weinmann et al., 1945 [4] | Two types based solely on phenotype: hypoplastic and hypocalcified |
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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) |