What is Molar Incisor Hypomineralisation (MIH)?

Molar Incisor Hypomineralisation (MIH) is a condition which can affect adult molar and incisor teeth. MIH affects tooth enamel and dentine, making them softer than normal. MIH enamel can often look unnaturally white, creamy yellow or brown.

In some severe cases, such as in the picture below, the enamel is a creamy brown colour and so soft that a large "pothole" has formed. Often these potholes start out being simply the result of MIH and have nothing to do with decay (dental caries).

Problems with MIH

  • Sensitivity (dental pain)
  • Crumbling and potholes leading to increased risk of decay (dental caries)
  • Unsightly appearance in the case of front teeth.

Dentists can also have problems when trying to fix these defective teeth. So, although patients with MIH can be perfectly healthy in all other regards, it's possible their dental condition can be quite troublesome if not cared for well.


In MIH, the dental pain might be triggered by hot or cold foods or tooth brushing. The pain can vary from a mild sensitivity to very severe affecting daily life. MIH can be painful even if there is no evidence of potholes, or dental caries showing. In other words, even patients who have taken great care to keep their mouths free of decay (and fillings) can unfortunately end up with bad toothache as a consequence of MIH.

Tooth Decay

More advanced cases of MIH do have a higher risk of getting decay (dental caries) for several reasons. 1. When enamel is soft rather than shiny hard, the "bugs" (bacteria) that cause tooth decay can penetrate the tooth more easily. This situation only gets worse when the enamel is soft and crumbly, giving more places for bacteria to hide.

2. The extreme sensitivity of some MIH teeth can stop people brushing in that part of the mouth, so increasing the risk of dental decay (caries).


Unsightly front teeth may lead to anxiety for the patient. In some cases simple treatments can improve the cosmetic appearance of front teeth, and often these work well with smaller patches of affected enamel.

In severely affected molars however, the softer enamel can mean these teeth are harder to fix and fillings don't last as long as normal. Another problem is that sensitive MIH teeth can be slow to numb with local anaesthetic. For these reasons, your dentist might suggest using inhalation sedation (laughing gas).

In severe cases extraction (removal) of the affected molars will be advised, after being assessed by an orthodontist (a dentist specialising in braces). In some circumstances the opposite unaffected teeth will also be removed to prevent further biting problems.

There are different treatment options which your dentist can discuss with you. In some cases you may need to see a specialist before a decision can be made.

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