AtlasDevelopmentalAmelogenesis Imperfecta

Developmental Disorders

Amelogenesis Imperfecta

aka AI · Hereditary Enamel Defects

Group of inherited disorders affecting enamel formation resulting in hypoplastic, hypomature, or hypocalcified enamel.

Gene examples
AMELX, ENAM, MMP20, KLK4
Classification
Witkop (Types I-IV)
Treatment
Crowns, veneers, implants

§ 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

  1. Witkop CJ. Am J Med Genet 1988;28:345
  2. Neville BW. Oral & Maxillofacial Pathology, 4e

Draft — pending faculty review. Educational use only; verify against current guidelines and primary sources before clinical application.