Molar Incisor Hypomineralisation

Question 1

What is MIH?

Answer 1

• Developmental condition
• Hypomineralisation of systemic origin affecting 1 to 4 permanent first molar(s)
• Frequently associated with affected incisors

Question 2

Define ‘hypomineralised enamel’

Answer 2

• Disturbance in enamel formation (matrix is normal)

- Resulting in reduced mineral content

Question 3

Define ‘hypoplastic enamel’

Answer 3

• Reduced bulk/ thickness of enamel (matrix is abnormal but mineralisation is normal)
• TRUE = enamel never formed
• ACQUIRED = post-eruptive loss of enamel bulk (so brittle it breaks down and looks like it never formed)

Question 4

When is the ‘critical period’ for the formation of MIH?

Answer 4

• General first year of life

- Enamel matrix of permanent FPM crown formed by 1yr

Question 5

What is the aetiology for MIH?

Answer 5

PRENATAL

• No definitive cause
• Mother’s general health in 3rd trimester?

NATAL
- Traumatic birth (anoxia, hypocalcaemia)

POST-NATAL

• Breast-feeding length
• Fever & med
  
  • -> Infection (measles, rubella, varicella)
• Socio-economical status

Question 6

Describe the clinical appearance of MIH

Answer 6

• Soft, porous, discoloured ‘chalk’
• White, yellow or brown lesions
• CLEAR demarcation between affected and normal enamel

Question 7

What are the pain mechanisms in MIH?

Answer 7

• Dentine hypersensitivity = enamel porosity/ exposed dentine –> fluid flow activating A-delta nerves (hydrodynamic theory)
• Peripheral sensitisation = pulpal inflammation –> C-fibres

Question 8

What are the clinical problems associated with MIH?

Answer 8

• Loss of tooth substance (caries)
• Sensitivity
• Aesthetics

Question 9

How is MIH managed?

Answer 9

MOLARS

• Composite/ GIC restorations
• Crowns (including SSC)
• Extraction (consider age/ ortho)

INCISORS

• Microabrasion
• (+/-) external bleaching
• Veneers = composite, porcelain