Molar Incisor Hypomineralisation
Molar Incisor Hypomineralisation (MIH)
- Last updated February 5, 2026
✅ Objectives
By the end of these revision notes, you should be able to:
- Define molar incisor hypomineralisation
- Understand the potential aetiology and risk factors
- Recognise the clinical features of molar incisor mineralisation
- Understand principles of management of patients with molar incisor hypomineralisation
What is Molar Incisor Hypomineralisation?
Molar incisor hypomineralisation (MIH) is a developmental enamel defect affecting one or more of the first permanent molars and often associated with involvement of permanent incisors. It is characterised by hypomineralised and poor quality enamel that is usually of normal thickness.
Key issues with MIH include:
- Higher caries risk
- Hypersensitivity
- Increased risk of post-eruptive enamel breakdown
- Complex and challenging restorative and patient management
Aetiology
MIH occurs due to disruption in enamel mineralisation during the late maturation phase, affecting teeth forming from birth to around 3 years of age – hence first permanent molars and permanent incisors.
MIH is thought to be a multifactorial condition with multiple potential factors impacting its development. It should also be noted that MIH is not caused by poor oral hygiene and by fluoride exposure.
Systemic Factors
- Childhood illness e.g. chickenpox
- Pyrexia
- Perinatal complications e.g. prematurity
- Hypoxia
- Low birth weight
- Maternal illness during pregnancy
Others Factors
- Use of antibiotics
- Some evidence suggests there may be a genetic predisposition to MIH
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