Dental esthetics, especially of the anterior teeth, is of great importance in our society. Hypomineralizations in the area of the incisors primarily appear as opacities of different shades and extensions. White-yellowish opacities are less severe than yellow-brownish discolorations (Fig 15-1). Posteruptive enamel breakdowns and hypersensitivities are possible but occur less frequently compared to molars (Fig 15-2).¹ Opacities in the anterior region interfere with the esthetic appearance and may impair quality of life.

Fig 15-1 MIH-affected tooth 21 with whitish opacity.

Fig 15-2 MIH-affected teeth 11 and 21: Both teeth show opacities, tooth 11 additionally shows a posteruptive enamel breakdown at the incisal edge.

Not only in adults, but also in young patients, developmental enamel disorders can have psychosocial effects.² Already children with clearly visible opacities on the incisors may be exposed to discriminatory social judgments from peers due to the false assumption of their counterparts that they do not care about their appearance or are lacking in brushing their teeth.³ If patients report such situations, treatment should be considered based on age and a risk-benefit ratio.⁴ Treatment planning should be done cautiously and delayed as long as possible, as immature permanent teeth are characterized by a large and sensitive pulp.¹

In the following, some treatment options for anterior teeth with MIH are presented that could be used alone or in a combination to achieve better esthetic appearance results for affected patients. These include bleaching, microabrasion, infiltration, and minimally invasive restorative treatment.

15.1 Bleaching

Bleaching includes the noninvasive possibility of whitening teeth. It is suitable for both individual discolored teeth and for whitening the entire dentition. Most bleaching materials contain hydrogen peroxide (H₂O₂) or carbamide peroxide (CH₆N₂O₃).⁵ Hydrogen peroxide is characterized by a low molecular weight. It is therefore able to penetrate through enamel and dentin and produce free oxygen radicals inside the tooth.⁵ In this way, yellow pigments (xanthopterins), for example, are oxidized to white pigments (leucopterins). Hydrogen peroxide must act sufficiently long and frequently enough in situ to remove discoloration by oxidation. Carbamide peroxide is a complex hydrogen peroxide substance. Thus, the mechanisms of action of the two materials are identical. One-third of the carbamide peroxide concentration separates into the active hydrogen peroxide and two-thirds into urea (CO(NH₂)₂). The latter subsequently splits into ammonium and carbon dioxide and is irrelevant to the reaction.

In the context of bleaching therapy for MIH-affected teeth with opacities, the aim is to increase the overall brightness of the teeth so that the contrast with the (usually white) opacity is decreased. Thus, the fading of the opacity itself is not the main focus.6 This option can already be used in adolescents.¹

Possible side effects to be expected with bleaching treatment are sensitivity, mucosal irritation, and enamel surface changes.⁷

Home bleaching with 10% carbamide peroxide gel in a customized tray is the gentlest bleaching method prescribed by the dentist.⁸ The chemical and mechanical properties of sound and hypomineralized enamel are not affected.⁹ For better protection, the combination with a CPP-ACP paste seems to be useful. CPP-ACP protects the tooth structure and remineralizes the opacities during the bleaching process without compromising the bleaching effect.⁸

Clinical case 1

Figure 15-3 shows bleaching therapy in a 16-year-old patient who presented in the dental office for treatment of the anterior teeth following trauma of tooth 22 and, in addition to restoration of the fractured tooth, also requested treatment of the disturbing discolorations in the anterior upper jaw. Individual bleaching trays were made to mask the opacities and the patient was instructed to wear them at night using 10% carbamide peroxide for a period of 3 weeks. The originally planned additional further treatment with the infiltration technique (Icon, Fa. DMG, Hamburg, Germany) was cancelled as the patient was already satisfied with the result after bleaching.

Fig 15-3 Bleaching treatment in a 16-year-old patient with discoloration in the maxillary anterior region (source: Clarence Tam). a) Initial situation. b) Situation after 2 weeks. c) Final situation after 4 weeks.

15.2 Microabrasion

Microabrasion removes a small amount (no more than 100 μm) of surface enamel by abrasion and erosion with abrasive and acidic pastes. This leads to changes in the optical properties and can improve the esthetic appearance of the teeth.¹⁰

However, as a sole medium, microabrasion has limited utility in the esthetic treatment of hypomineralized incisors.^4,6,11 Studies have suggested the use of microabrasion prior to the home application of CPP-ACP pastes to optimize their remineralization results in white spot lesions.^10,12

In the treatment of opacities in MIH-affected anterior teeth, this procedure is often used as a pretreatment before the infiltration technique described next.

15.3 Infiltration

15.3.1 Background

The principle of infiltration has been used for many years in cariology to mask white spot lesions. Originally, the infiltration technique was developed for early to moderate stages of enamel caries in the proximal space, which show pronounced demineralization of the enamel below an apparently intact surface. The aim here is to seal the porosities of the enamel caries (in particular the lesion body) with light-curing resins, the so-called infiltrants, in order to block the diffusion pathways of cariogenic acids and subsequently to slow down or even arrest the caries process.¹³ In addition, it has been observed that the enamel areas of carious lesions lose their whitish appearance after infiltration and visually resemble sound enamel again.

This masking is based on a change in the refraction of light within the enamel lesion. While sound enamel and carious lesions have different refractive indices, carious enamel infiltrated with resin approaches the refractive index of sound enamel again, so that the caries appears much less whitish than before infiltration.¹⁴

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