Developmental Disorders
Amelogenesis Imperfecta
aka AI · Hereditary Enamel Defects
Group of inherited disorders affecting enamel formation resulting in hypoplastic, hypomature, or hypocalcified enamel.
§ figuresFigures (3)
Fig. 1amelogenesis imperfecta, hypoplastic type. Note the association of pitted enamel and open bite.
“B amelogenesis imperfecta” · see above · CC BY 2.0 · Wikimedia Commons
Fig. 2amelogenesis imperfecta, hypomineralised type. The enamel is rough, soft and discoloured.
“E amelogenesis imperfecta” · see above · CC BY 2.0 · Wikimedia Commons
Fig. 3Amelogenesis imperfecta, hypomineralised type. The enamel is rough, soft and discoloured. In this case it's part of cone rod dystrophy syndrome. Various enamel defects (both hypoplastic and hypomineralised) coexist in th
“F amelogenesis imperfecta” · see above · CC BY 2.0 · Wikimedia Commons
Verified open-access images only, reproduced for education under their stated licences · no AI-generated or illustrative artwork · Amelogenesis Imperfecta figures pending faculty review.
§ overviewOverview
Genetically heterogeneous conditions with enamel abnormalities without systemic disease.
§ icdICD Classification
K00.5
§ etiologyEtiology
- 01Mutations in AMELX, ENAM, MMP20, KLK4, FAM83H genes
- 02Autosomal dominant, AR, or X-linked inheritance
§ epidemiologyEpidemiology
Prevalence 1:700 to 1:14,000 depending on population.
§ pathogenesisPathogenesis
Defective amelogenin secretion (hypoplastic), impaired enamel matrix removal (hypomature), or deficient mineralisation (hypocalcified).
§ clinicalClinical Features
- 01Thin, pitted or absent enamel (hypoplastic type)
- 02Soft, cheese-like enamel (hypocalcified)
- 03Opaque, mottled enamel (hypomature)
- 04Anterior open bite common
- 05Tooth sensitivity
§ differentialDifferential Diagnosis
- 01Fluorosis
- 02Dentinogenesis imperfecta
- 03Molar-incisor hypomineralisation
- 04Chronological hypoplasia
§ histopathHistopathology
- 01Reduced enamel thickness or prismatic disruption
- 02Dentin normal
§ radiographicRadiographic Features
- 01Thin or absent enamel with normal dentin contrast (hypoplastic)
- 02Enamel and dentin similar radiodensity (hypocalcified)
§ investigationsInvestigations
- 01Clinical + family history
- 02Genetic testing for confirmation
§ classificationClassification
- 01Type I — Hypoplastic (14 subtypes)
- 02Type II — Hypomature (6 subtypes)
- 03Type III — Hypocalcified (4 subtypes)
- 04Type IV — Hypomature-hypoplastic with taurodontism
§ treatmentTreatment
- 01Preventive fluoride varnish
- 02Composite restorations / veneers
- 03Full-coverage crowns for severe cases
- 04Overdentures or implants long-term
§ complicationsComplications
- 01Rapid attrition
- 02Caries susceptibility
- 03Aesthetic and psychosocial impact
§ prognosisPrognosis
Good with early restorative intervention; lifelong dental maintenance required.
§ examKey Examination Points
- 01Classify by Witkop classification
- 02Distinguish from DI by dentin appearance
- 03X-linked forms affect males more severely
§ revisionQuick Revision Summary
- 01AI = enamel only, DI = dentin only
- 02Type III hypocalcified = soft, rapidly lost enamel
- 03AMELX mutation = X-linked hypoplastic
§ vivaBDS Viva Questions
- 01What genes are implicated in AI?
- 02How do you differentiate AI from fluorosis?
- 03Describe the Witkop classification.
§ mcqsMCQs — Assessment (3)
Question 1
Which type of AI results in enamel that chips away easily after eruption?
Question 2
AMELX mutation causes which inheritance pattern?
Question 3
Which condition affects ONLY dentin?
References
- Witkop CJ. Am J Med Genet 1988;28:345
- Neville BW. Oral & Maxillofacial Pathology, 4e
Draft — pending faculty review. Educational use only; verify against current guidelines and primary sources before clinical application.