Overview

Molar incisor hypomineralisation (MIH) is a tooth condition that affects the growth and hardening of some teeth.

In MIH, the outer layer (enamel) and middle layer (dentine) of the tooth are softer than usual because they have not developed properly. This can lead to tooth decay occuring more easily in affected teeth.

About 1 in 8 people in the UK have MIH of some type. Some people might have a mild form, and not realise they have MIH.

Working with our orthodontic colleagues, we can help to plan longer-term management of affected adult first molar teeth. This means that you might need to wear a brace.

If your child does not have treatment for MIH, the affected teeth can continue to break down.

Read our information about dental decay in children

Read the NHS information about looking after your children's teeth

Symptoms of MIH

Common features of MIH include:

• increased tooth sensitivity
• teeth might become discoloured (cream, yellow or brown)
• teeth might be painful
• teeth tissue might break down (become crumbly)

MIH is usually noticed when the child’s adult front teeth (incisors) and adult back teeth (molars) come into the mouth. This is usually when the child is about 6 to 7 years old.

If MIH affects the baby teeth, it can be seen on the back teeth from 2 to 3 years old.

The adult first teeth can be affected by MIH. It might affect just 1 tooth, a few teeth, or all of them.

Causes of MIH

MIH is thought to be caused by a disturbance in tooth development that happens at about the time of birth, or in the first few years of life.

The cause is not fully understood, but severe childhood illnesses, high fevers, and a traumatic birth have all been suggested as possible causes.

Diagnosing MIH

Your child’s dental team will do a full examination to diagnose MIH.

They might take X-rays, if they are needed.

They will ask about your child’s medical and family history. This can help them find any possible causes of MIH, and rule out any other causes of enamel problems.

Treating MIH

If your child’s teeth are sensitive and broken down, they will need treatment.

If your child does not have treatment, the teeth can continue to break down, which can lead to:

• pain
• sensitivity
• the nerves in the tooth being affected, which can increase pain or lead to infection
• a build-up of pus (abscess)

If your child has an infection or an abscess, or their tooth is so broken down that it cannot be filled, it might need to be removed (extracted).

There are different types of treatment depending on which teeth are affected, and how bad the condition is.

Your child’s dentist will talk to you about the treatment options, and help you and your child decide on the best one for you.

Front teeth

Front teeth are treated to help manage sensitivity and poor appearance.

Treatment can also improve the rough surface of the tooth, or any breakdown.

A combination of treatments can be used, depending on response to treatment.

• Fluoride varnish can be painted on the teeth every 3 months to help with sensitivity.
• Acid pumice microabrasion uses acid and a dental polishing powder to remove the outer layer of the tooth to improve the appearance.
• Resin infiltrant improves the appearance of teeth by changing how light reflects off the teeth.
• White filling is a thin layer added over the front of the tooth. This will fill any areas that have broken down, and help with discolouration. It will also make the tooth thicker.

Back teeth

Back teeth are treated to help with sensitivity and breakdown, but not always for appearance.

Treatment will depend on how decayed or broken down the teeth are, and if they're likely to last in the long term.

• Fissure sealants cover and protect the natural grooves in the teeth. This is used in mildly affected teeth.
• Stabilisation or a white filling involves either a temporary filling with no drilling of the tooth, or a filling with drilling of the tooth. Your dentist will advise you which is best for your child.
• A stainless steel crown is a silver-coloured metal cap which is put on the tooth. This is recommended for a decayed or broken down tooth if the longer-term plan is to remove the tooth (extraction).
• Removing the tooth might be necessary if it's heavily broken down. If this is done at the right time, it can allow adult teeth to move naturally into the gaps and close any spaces.

Things you can do to help your child

Support your child with toothbrushing, especially of the affected teeth which they might avoid because they are sensitive.

Milder forms of MIH, where sensitivity is the main issue, might be helped by your dentist painting fluoride varnish onto your child’s teeth every 3 months.

This can also help to reduce the chance of more breakdown or decay.

If your child is 7 years or older, they can use a fluoride mouthwash.

If your child is 10 years or older, they can use a double-strength adult toothpaste (on prescription).