His New Molars Came Through Already Broken

Quick answer: Molar incisor hypomineralisation means the enamel on the first permanent molars formed incorrectly before the tooth ever erupted. It is not decay and it is not caused by anything the family did. It is exquisitely sensitive, it crumbles under normal chewing, and it needs treating differently.

The call

Two things did not fit together. He would not let his mother brush the back teeth, and he had never eaten anything cold in his life without complaining.

Yoni, 7, from Givat Sharett, had been to a previous practice where he had been told he had decay from poor brushing. His mother, who supervised his brushing twice daily, had not found that convincing.

What we found

All four first permanent molars affected, to differing degrees — which is characteristic. Two showed creamy-white and yellow-brown patches with sharply demarcated borders. The upper right molar had lost enamel entirely from one cusp, with the surface crumbled away and dentine exposed.

Two upper incisors had smaller creamy-white patches on their outer surfaces.

How this differs from the other white patches, which is the diagnosis that gets missed:

• Fluorosis is symmetrical, diffuse-edged, hard and glossy. This was asymmetrical, sharply demarcated, and soft.
• Early decay appears after eruption, at plaque-retentive sites. This was present the moment the teeth came through.
• MIH is present from eruption, asymmetrical, sharply bordered, creamy-white to yellow-brown, and — the defining feature — the enamel is porous and soft, and it breaks down under ordinary chewing forces rather than from decay.

The colour predicts the behaviour. White-cream patches are usually more stable. Yellow-brown patches are more severely affected and break down sooner.

Why it hurts so much. The porous enamel lets stimuli through to the pulp far more readily, and there is evidence of chronic pulpal inflammation in these teeth even before any breakdown. The practical consequence for a seven-year-old is that cold, air and brushing all hurt — which is why he avoided brushing there, which then produced genuine decay on top of the underlying defect.

Local anaesthetic works less reliably in MIH molars, for the same reason. Telling parents this in advance matters, because a child who is told it will not hurt and then feels it loses trust in a way that is hard to recover.

The cause is not established. Illness, fever or antibiotic use in the first years of life, when these teeth are mineralising, are all associated. Nothing the family did or failed to do explains it, and that needed saying explicitly.

What we did

Named it, which was most of the value of the first appointment. His mother had been carrying two years of implied criticism about her son's brushing.

Desensitised first. High-fluoride varnish every three months and a casein-phosphate paste at home, which reduces sensitivity enough to make brushing possible — and brushing was the immediate priority, since the sensitivity was driving genuine decay.

Sealed the two mildest molars with a bonded sealant, having first treated the surface to improve bonding. Adhesion to hypomineralised enamel is poor and standard technique fails.

Stainless steel crowns on the two worst molars. These are pre-formed metal crowns cemented over the tooth, and for a badly affected MIH molar in a child they are the most durable option by a wide margin. They cover the whole tooth, stop the crumbling, remove the sensitivity completely, and last until the tooth can be assessed properly in adolescence.

They are not attractive. In a seven-year-old's back teeth, invisible in normal conversation, that trade is worth making — and it avoided repeated failing fillings, which is what these teeth otherwise produce.

A long-term plan discussed early. Severely affected first molars are sometimes best removed at the right stage of development, around age eight to ten, so the second molars drift forward into the space. That decision needs an orthodontic opinion and correct timing, and raising it early gives the family time.

The incisor patches were left alone. They are cosmetic, and resin infiltration or microabrasion is available in the teenage years if he wants it.

The outcome

Sensitivity resolved within weeks of the crowns. He brushes without objection and eats ice cream, which his mother reports as the more meaningful measure.

At ten, an orthodontic assessment concluded the crowned molars could be kept. They remain sound at twelve.

What to do if this happens to you

1. Question a diagnosis of decay on newly erupted molars in a child with good hygiene.
2. Ask whether the enamel is hard or soft. That distinguishes MIH from fluorosis and staining.
3. Mention severe sensitivity to cold and brushing. It is a strong clue.
4. Ask about stainless steel crowns for badly affected molars. They outperform fillings substantially.
5. Warn the dentist that anaesthetic may work less well and ask them to plan for it.
6. Get an orthodontic opinion by eight to ten if the molars are severely affected.

Child's new back teeth chalky or crumbling? Ramat Beit Shemesh Urgent Dental Care will tell you whether it is decay or MIH. 055-985-8845 · WhatsApp https://wa.me/972559858845 · Harav Kook 28/1, Beit Shemesh

This is a composite clinical story. It reflects a presentation we see regularly in Beit Shemesh and Ramat Beit Shemesh; the name and details are illustrative and are not those of a real patient.