What is molar incisor hypomineralisation?

Molar incisor hypomineralisation (MIH) is a developmental condition which affects the enamel (outer layer) of teeth. The enamel is softer than usual and at a higher risk of developing decay. It often affects one or more of the adult molars (back teeth) and sometimes the incisors (front teeth).

Signs and symptoms

It's usually noticed around the age of six or seven, when the adult molars start to come through at the back of the mouth.

The teeth which are affected may be discoloured with a white, creamy, yellow or brown appearance, depending on the severity. The severity may vary between each affected tooth.

The teeth may be painful and/or sensitive to brushing or to certain foods and drinks. In more severe cases, areas of the teeth may crumble or break away easily. This is more common with affected back teeth.

What causes it?

The exact cause is not fully understood, however, it's thought a traumatic birth or a severe illness between birth and two-years-old may be linked. During this time, the affected teeth start to develop and as a result, any stress the body incurs may cause a disruption in tooth development, resulting in MIH. Sometimes there is no obvious identifiable cause.

How is it treated?

Treatment depends on the severity. For back teeth, treatment may involve:

• fissure sealants which is a coating to protect the grooves of the tooth
• fillings (temporary or permanent) if there is any decay or breakdown in the tooth
• stainless steel crowns which are silver coloured metal tooth-shaped caps
• tooth removal.

Stainless steel crowns or temporary fillings are often considered a temporary measure for stabilisation and to prevent further breakdown before the correct time for tooth removal.

Tooth removal is considered for more severe cases, where the prognosis of the tooth is poor. If carried out at the correct timing, this allows the adult tooth behind to grow into the space, leaving little to no gap. The correct timing for tooth removal will be determined by a radiograph (x-ray).

For front teeth, treatment may involve:

• fluoride varnish gel to help manage sensitivity
• micro-abrasion which uses an acidic polishing paste to remove the outer discoloured layer of enamel
• tooth whitening during adulthood to improve the aesthetic appearance
• white filling to improve the aesthetic appearance.

What happens if I do not get treatment?

If the molar teeth are moderately to severely affected, having no treatment can lead to breakdown and decay of the teeth. This is likely to cause pain and sensitivity.

If left untreated, the nerve can become exposed which hurts. The tooth will then require root canal treatment or removal.

What can I do to help?

• As the teeth are at an increased risk of decay, a low sugar diet and good oral hygiene is very important.
• Regular check-ups to check for any decay and to make sure the teeth are not getting worse are also helpful.
• For children aged eight and above, a fluoride mouthwash can be prescribed.
• For children aged 10 or older, a fluoride toothpaste can be prescribed.