Molar Incisor Hypomineralisation

"MIH"

In this section, we will cover:

1. What is MIH?
2. How is it caused? 
3. What are the signs and symptoms?
4. What are the treatment options?
5. Managing hypersensitive teeth 

How is it caused?

There are many theories on the causes of MIH but in the vast majority of cases, the cause is unknown.

 What we do know is it is caused by some sort of disturbance whilst the tooth is still developing under the gum. This is around the time of birth or in the first 3 years of life. Some of the proposed causes of MIH are:

• problems around birth including premature birth and lack of oxygen
• severe childhood illnesses 
• high fever 
• use of antibiotics

There is possibly a genetic factor involved in MIH but this has not yet been confirmed. 

What are the treatment options?

The type of treatment you need depends on which teeth are affected and how badly they are affected.

All children with MIH will benefit from:

1. Regular dental visits (usually every 3 months)
2. Regular fluoride varnish application
3. Using a high fluoride toothpaste which can be prescribed by the dentist:
   - Duraphat 2800ppm for children over 10 years old, or
   - Duraphat 5000ppm for children over 16 years old
4. Using a desensitising toothpaste or tooth mousse (if the teeth are sensitive)

Front teeth:
The main aims of treatment for front teeth are to decrease sensitivity and improve appearance. Options include:

• Fluoride varnish, tooth mousse and MI paste
  Fluoride varnish is applied by the dentist or other dental professional (nurse, hygienist, therapist).
  GC tooth mousse/MI paste can be bought over the counter, it cannot be prescribed. These two products contain special minerals (CPP-ACP) which strengthen the teeth. It is often useful to put a smear of this over the sensitive teeth just before bed to help with sensitivity. You should not use these if you have a milk allergy.
  These products aim to strengthen the teeth and decrease sensitivity. It will not change the appearance of the teeth.
  
• Microabrasion
  This uses an acid and polishing paste which removes the surface layer of enamel.
  This aims to lighten/remove brown patches on the teeth. It will not improve sensitivity.
• Resin infiltration
  This uses an acid which essentially opens up the "pores" in the enamel before infiltrating these pores with a runny tooth-coloured resin.
  This aims to reduce the appearance of white patches on the teeth (it does not work on brown patches on the teeth but it may be used following microabrasion if this has removed the brown patches). It will not improve sensitivity.
• Tooth whitening
  A special bleaching gel is placed inside a custom-made tray and worn overnight for approximately 2 weeks.
  This aims to blend the discoloured patches on the tooth with the unaffected teeth. It will not improve sensitivity - in fact, it may temporarily make sensitivity worse. In the UK, by law, whitening should not routinely be used in children under 18 years old. There are very few exceptions to this.
• Composite bonding
  A thin layer of white filling material is placed over the surface of the affected tooth to try to cover the discolouration. This does not involve any drilling and it will make the tooth appear thicker. This will require maintaining by the dentist as the filling will crumble and/or stain.
• Veneers
  The front surface of the tooth is drilled away and a thin layer of ceramic/porcelain (made in the lab) is glued onto the front of the tooth. This aims to mask the discolouration and may be an option you wish to consider as an adult. It is never the first choice of treatment as it involves drilling away the surface layer of your tooth and there are other more conservative options which may be more successful. 

Molars:
Treatment for first adult molars depends on how badly affected they are and how long they are likely to last. In general, we try to maintain adult teeth for as long as possible. However, if we catch MIH early and find the teeth are already crumbling or heavily decayed, it may be better to remove them at the ideal age (8-10 years old). Possible treatment options include: 

• Fissure sealant
  This is a coating which is applied to the grooves of the teeth to reduce the risk of decay. This can be used to protect mildly affected teeth.
• Dental filling
  Usually a temporary filling or a tooth-coloured filling material is used to restore the tooth to its natural shape. This aims to stabilise a tooth which has decayed or crumbled. In badly affected teeth, this is often a temporary measure until the ideal time for removing the tooth (8-10 years old). 
• Stainless steel crown 
  This is a silver-coloured tooth-shaped crown which is used for very badly broken down teeth to maintain them until the ideal time for removing them. 
• Dental extraction 
  For teeth with a poor long term prognosis, your dentist will discuss removing these teeth at the ideal age. If done at the right time, there is a high chance the second adult molars (which will still be under the gum at this point) will drift forwards and close the space where the first adult molars have been removed.
  Your dentist will usually discuss the case with an orthodontist to decide the best time to remove the teeth and which teeth to remove. Even if only the lower molars are affected, the orthodontist will often suggest also removing the healthy upper molars. This is to prevent them over-erupting (i.e. growing down into the space left by the lower molar). If your child is able to tolerate having their teeth removed in the dental chair, the upper molar can be monitored for signs of over-eruption. However, if they need to be put to sleep (a general anaesthetic), the upper molars will be removed at the same time. This avoids having to put your child to sleep again. 
  Occasionally, the orthodontist will recommend maintaining poor prognosis molars until your child is a teenager. This could be because your child's teeth are overcrowded (not enough space in the jaw for all the teeth to come through in a straight line) or if the upper teeth stick out much further than lower teeth.