Dental Update - Managing Young Patients with Molar Incisor Hypomineralization

Article

Molar incisor hypomineralization (MIH) is a developmental anomaly that affects the first permanent molar teeth and often the permanent incisors. Hypomineralization is a qualitative defect, ie there is a reduced mineral content in the enamel. MIH is a relatively common condition and it has a prevalence of 14.5% in the UK.¹

There is considerable variation in how MIH presents, from small areas of discoloration (Figure 1) to extensive post eruptive breakdown (PEB) (Figure 2).

Figure 1. Opacities in central incisors.

Figure 2. PEB in left maxillary first permanent molar.

Paediatric patients with MIH often present with difficulties eating or brushing their teeth due to sensitivity. They also tend to have cosmetic concerns and can often be bullied or teased at school.

The aetiology of MIH is unknown but multiple factors have been implicated:²

Respiratory disease;

Oxygen shortage in ameloblasts;

High fever diseases such as tonsillitis, chicken pox;

Environmental factors such as dioxins in breast milk;

Gestational problems.

Classification

Mild − lesion with only local colour change (white/opaque, yellow or brown) with smooth enamel surface;

Moderate − lesion with rough and broken enamel;

Severe − lesion affecting both enamel and dentine.

Both preventive and interceptive treatment may be required, depending on the severity of the condition.

The primary treatment aim should be to relieve the patient of pain or sensitivity, restore function and improve aesthetics.

Technique tips

Local anaesthesia

First permanent molars are often difficult to anaesthetize, even etch can cause considerable sensitivity.

In order to achieve adequate anaesthesia, IDN blocks with lidocaine may be necessary. Articaine infiltrations can be considered as this can provide superior analgesia over lidocaine.³ Care must be taken when delivering articaine due to its prolonged numbness. Inhalation sedation can also be a useful adjunct.

Managing 6s

Acid etch composite (AEC) is the material of choice in restoring molars with minimal PEB. However, as there is often poor quality enamel-bond strength, GIC can be the second line material in considerably hypomineralized teeth when AEC fails.

Restorations often fail in severely hypomineralized molars therefore extra-coronal structures, such as preformed metal crowns, can be considered. Pre-formed metal crowns can be placed over two visits. Visit one for placement of orthodontic separators (Figure 3) and visit two for removal of the separator and placement of preformed metal crown (Figure 4).

Be aware that interceptive extractions of first permanent molars is often the treatment of choice in severe cases of MIH.^4,5 Excellent results can be achieved if planning the loss of first permanent molars is timed correctly. Before placing any restorations in the first permanent molar teeth in children younger than 9 years old, always consider the aetiology of the tooth loss and the long-term prognosis.A second opinion can be sought from a specialist or consultant in paediatric dentistry or an orthodontist. Early assessment of poor prognosis first permanent molars is essential and should be at around 8−9 years of age. The ideal time to arrange extraction is when the bifurcation of the unerupted mandibular second permanent molars is fully formed, and the lateral incisors are fully erupted (Figure 5). It is preferable for third permanent molars to be present when considering extractions of first permanent molars.

Managing Incisors Incisors rarely undergo PEB. Treatment options to improve aesthetics include:

Leave and monitor if no symptoms or aesthetic concern.

Conservative treatment options involve tooth whitening and/or microabrasion.⁴

Microabrasion is a technique using a slurry of pumice and acid etch (usually 35% phosphoric acid), which can be applied to the buccal surface of a tooth using a rubber cup or bristle brush (Figure 6). Alternatively, 6.6% hydrochloric acid with silicon carbide particles may be used or 18% hydrochloric acid. Microabrasion works both chemically and mechanically to remove superficial stains and irregularities of the enamel (Figures 7 and 8).

If there is an area of discoloration which is deep and beyond the scope of microabrasion, the area of discoloration will need to be removed and a composite restoration can be placed.

Veneers may be considered for adult patients in severe cases, however, due to the amount of sound tooth removal involved, conservative management of composite restorations or tooth whitening is generally the treatment of choice.