The mysterious tooth condition affecting millions of children

Your child’s small, delicate, chalk-white baby teeth fall out. In their place grow yellowish-brown, fragile teeth – much to everyone’s surprise.

This is the dental condition molar incisor hypomineralisation (MIH), a condition that is almost as common as tooth decay, though hardly known about outside of dentistry – and even then it can often be misdiagnosed.

The condition affects how certain adult teeth form in early childhood. It isn’t caused by lack of brushing, sugar or poor dental habits, but by something that disrupts the enamel formation before the teeth even erupt.

In our work at the teaching clinic at the University of Copenhagen dental hospital, we see many children and young people needing help for this condition.

It affects around 28% of children in Scandinavia and is one of the most widespread dental conditions. Studies show that it’s very common across Europe, while it appears to be less of an issue across Africa and Asia.

Researchers are still trying to figure out why this is the case, though it’s suspected to be largely due to differences in diagnosis and reporting, along with the prevalence of early childhood illnesses and genetic factors.

At the moment, MIH is still something of a puzzle for dentistry. We know it affects a significant number of children and can leave their adult teeth permanently weakened and discoloured.

But we don’t fully understand why some children develop it while others don’t. What is clear, though, is that it’s more common than many people realise.

Here’s what we know so far based on the current research.

What is MIH?

Enamel is the thin outer layer of our teeth and the hardest material in the body. But in children with MIH, the development of the tooth enamel has been disrupted, leaving it with fewer minerals.

This disruption occurs early in a child’s life, while the teeth are forming inside the jaw. Typically, this happens from around birth until about the age of two.

As a result, the teeth look different and can break more easily.

Most often, the enamel on the first permanent molars, the so-called six-year molars, and the front teeth are affected.

As well as the visible signs, children may also avoid brushing their teeth because it hurts – and can find that cold and hot food or drinks cause tooth sensitivity.

Research points to five possible causes of MIH. This includes:

What can parents do?

First off, it’s important to know that, with the knowledge we have today, MIH itself cannot be prevented. So, as parents, there’s nothing you can actually do to stop the condition from occurring.

That said, there are things you can do to help. The most obvious one is tooth brushing and the use of fluoride toothpaste. This is extremely important because the tooth enamel is softer in young children, so the teeth are harder to keep clean and are at greater risk of cavities.

It’s also important to help your child develop a good relationship with the dentist. It helps to speak positively about what dentists do for teeth: namely, helping to protect them better so they do not hurt or break. It’s also important to tell your child that they should say where and how a tooth hurts, if it does.

What can the dentist do?

If your child does have MIH, the dentist will assess how extensive the condition is and classify the affected teeth as mild, moderate or severe.

Molars with mild MIH are treated with concentrated fluoride gel or sealed with a transparent plastic coating to help protect them from cavities, or both.

Molars with moderate MIH will receive temporary fillings and because the tooth is very sensitive, anaesthesia is needed.

Molars with severe MIH receive fillings and, in the most serious cases, a stainless steel crown. This is a kind of foil cap that protects the tooth from breaking and from cavities and pain.

In rare cases, the dentist may suggest removing the tooth altogether if its long-term prognosis is too poor. This typically happens between the ages of eight and ten.

Front teeth usually only have mild to moderate MIH and so are often not treated initially.

When children with MIH get a little older, they often ask for a more aesthetic treatment. This will typically involve whitening combined with a newer type of treatment in which a thin, fluid resin can be infiltrated into the enamel.

The resin will fill the empty spaces in the enamel structure and so the apparent discolouration will disappear, leaving a tooth with a normal, smooth crown colour.

In adulthood, severely affected molars may benefit from a crown or a porcelain inlay.

What now?

To really tackle this condition and its effect on children’s teeth, we first need a clearer picture of how widespread it actually is. That means stronger, more consistent studies — and a better agreement across the profession on how the condition is diagnosed and recorded.

At the same time, researchers are still working to answer some of the most basic questions: what are the key triggers? And why do some children develop it while others don’t?

In the long run, more research will not only improve treatment but also help prevent the condition from causing long-term dental problems, thus reducing the need for repeated, often difficult dental care in children (and adults).

This article was commissioned as part of a partnership between Videnskab.dk and The Conversation, where articles are also published in Danish.