Molar Incisor Hypomineralisation (MIH)

Molar Incisor Hypomineralisation (MIH) is a dental condition which affects the enamel (outer layer) of permanent (adult) teeth. It makes it softer than normal. It commonly affects the first permanent molars, permanent incisors and sometimes permanent canine teeth. One, some or all of the molar teeth can be affected.

How common is it?

An estimated one in eight children in the UK are affected by MIH.

What does MIH look like?

Normal enamel is white and hard but teeth affected by MIH have poor quality enamel (outer layer) with white, yellow or brown discolouration.

What causes MIH?

It is thought to be caused by a disturbance in tooth development at the time of birth or in the first few years of life. The exact cause of MIH is unclear, although several factors like severe childhood illness, high fevers, exposure to environmental pollutants, low birth weight or the use of antibiotics have all been suggested.

How can MIH affect my child?

The teeth affected can be sensitive or painful, especially while tooth brushing. With the poor quality tooth structure, they can be crumbly which can lead to rapid development of dental decay. Parts of the teeth affected can chip off. The teeth can also exhibit wear. The front teeth usually do not get affected as severely. The front teeth can have white or yellow patches on them that children may find displeasing to look at, especially when they smile. The affected teeth can be more difficult to numb up with a local anaesthetic for dental treatment. At what age does this occur? It usually presents when the first adult molars and the upper front adult incisors start to erupt at the age of 6 to 7 years.

What treatment does MIH require?

Molar teeth

The dentist will consider how decayed or broken down the teeth are and whether they are likely to last long term.

  • Regular fluoride varnish: decreases sensitivity
  • Fissure sealants: to cover and protect the natural groves in mildly affected teeth
  • Fillings: either temporary fillings to stabilise the tooth or a filling with drilling the tooth
  • Preformed metal crowns: a silver coloured cap for more decayed/broken down teeth to temporise them
  • Tooth removal (extraction): if the tooth is of very poor quality, it may need to be removed. Extractions done at the right time allow other adult teeth to move to minimise gaps. This may sometimes require a specialist opinion from an orthodontist as well.

Front teeth

Front teeth are sometimes treated to improve poor appearance/roughness.

  • Regular fluoride varnish: decreases sensitivity
  • Microabrasion: treatment to remove a very thin layer of the outer layer of the tooth enamel to improve appearance
  • White filling: a thin layer of a white filling is added over the front teeth to mask the discolouration

Produced by the Community Dental Service, September 2021. Revision due September 2023. Version: 1.0 ©The Rotherham NHS Foundation Trust 2021. All rights reserved. 

Did this information help you?

  • Page last reviewed: 10 February 2023
  • Next review due: 10 February 2024