Key concepts for clinical management of Molar Incisor Hypomineralization

Abstract

Clinical management of patients with molar incisor hypomineralization (MIH) requires a comprehensive and multidimensional assessment that integrates clinical, behavioral, radiographic, functional, and psychosocial parameters. This article discusses key aspects of MIH management, including diagnosis and severity grading; non-invasive strategies aimed at preventing enamel breakdown; restorative management of severely affected molars, including the role of timed extractions; esthetic treatment to mask opacities in anterior teeth; and desensitizing approaches for the management of hypersensitivity. The literature for this narrative review was identified through targeted searches in PubMed for classic and recent publications on the clinical management of MIH. Reference lists of relevant articles were also hand-searched to identify additional relevant studies. Finally, future perspectives and emerging directions in MIH management are discussed.

A holistic approach to the diagnosis and prognosis of affected teeth in children with MIH

Molar-incisor hypomineralization (MIH) is a developmental enamel defect that presents significant clinical challenges beyond the structural integrity of affected teeth. From an epidemiological perspective, MIH has emerged as a significant public health concern due to its high prevalence, worldwide distribution, and substantial impact on oral health and quality of life. MIH affects a considerable proportion of children globally, with a pooled global prevalence estimated at approximately 13.1%, and values that vary according to diagnostic criteria, age groups, and study populations.1

An accurate diagnosis and reliable prognosis require a comprehensive, multidimensional assessment that integrates clinical, behavioral, radiographic, functional, and psychosocial factors.2, 3 The diagnostic process begins with a detailed medical and dental history, including prenatal, perinatal, and early childhood conditions, as systemic disturbances during amelogenesis have been associated with the multifactorial etiology of MIH.4

The clinical examination should systematically evaluate morphological characteristics of enamel defects and radiographic assessment complements these findings by revealing pulpal involvement, hidden caries lesion and restoration defects. Moreover, MIH management should follow a holistic and child-centered approach, addressing not only the affected teeth but also the child’s functional, emotional, and behavioral needs. Treatment planning should consider factors such as pain perception, dental anxiety, treatment tolerance, and oral health-related quality of life.4 In addition, preventive and therapeutic strategies, including caries prevention, desensitization protocols, minimally invasive restorative interventions, and long-term follow-up, should be individualized according to each patient’s clinical characteristics and needs.5

Clinicians must also recognize the emotional and psychosocial burden associated with MIH. Children presenting visible anterior defects may experience reduced self-esteem, social embarrassment, and impaired social interactions, while chronic hypersensitivity may negatively affect eating habits, oral hygiene practices, sleep quality, and overall daily comfort.6 Moreover, children affected by MIH frequently experience hypersensitivity and repeated dental interventions, which may negatively influence cooperation and increase fear and anxiety during dental treatment.7 Addressing these concerns may improve treatment acceptance, adherence, and overall quality of life.

Therefore, contemporary treatment protocols to MIH management should integrate individualized clinical decision-making with strategies aimed at improving both oral health and patient well-being over time.

Diagnosing, grading and staging severity

Since MIH was recognized and described as a specific condition,2 there has been a need to propose diagnostic criteria to identify and assess its severity in the clinic. The EAPD (European Academy of Paediatric Dentistry) criteria was proposed in 20038 and reinforced in an updated policy document published in 2022.5 One advantage of the EAPD criteria is that they combine clinical aspects identified in the teeth with symptoms and concerns reported by the patient, resulting in diagnosis at the patient level. However, no color differentiation was suggested for teeth presenting only opacities. In addition, no distinction was made between post-eruptive enamel breakdown (PEB) restricted to enamel and PEB exposing dentin, nor between PEB occurring alone or in combination with caries lesion. In an attempt to overcome these limitations, the updated EAPD policy document5 suggested incorporating the grading systems proposed by Ghanim et al.9 to differentiate white-creamy from yellow-brownish opacities and to identify atypical caries lesions in teeth presenting PEB.

It has been extensively demonstrated that the darker the opacity, the lower the mineral and the higher the protein content of the enamel.10, 11, 12, 13, 14 Moreover, the validity of differentiating opacities in white-creamy and yellow brownish categories has been demonstrated in longitudinal clinical studies showing that darker opacities are at a higher risk of breakdown over time.15, 16, 17, 18, 19, 20 Therefore, when screening teeth for MIH, it is advisable to use a scoring system that grades not only the level of surface integrity (enamel or dentin), but also the color of the opacities not showing post-eruptive enamel breakdown.

Discriminating between PEB with or without caries lesion may be challenging. Not all PEB will necessarily evolve into caries lesion. A PEB exposing dentine, where plaque accumulation and soft dentine are observed, will be considered carious. According to the diagnostic criteria, caries lesions surrounded by hypomineralized enamel and/or involving tooth surfaces which are usually not affected by caries will be scored as atypical caries lesion.9

Figure 1 presents an examination flow, collecting clinical data from the patient level to the tooth surface level.

Figure 1. Flowchart recommending the assessment of clinical data at the patient level, mouth level, and tooth level during the examination of patients affected by MIH.

The association between MIH and caries deserves a comprehensive discussion. Several studies have reported that MIH patients present higher caries prevalence and higher caries index scores compared with those without MIH.21, 22, 23 As most of the studies are based on the DMF-T index, their results may overestimate the occurrence of caries because fillings are not necessarily placed due to caries, and enamel breakdown exposing dentin may be scored as cavitated caries even when no carious lesion is present. Therefore, the questions whether MIH increase the caries index or the need for restorative treatment is genuine in this context. Higher DMF-T values in MIH-patients reflect into a greater treatment need in permanent teeth but not necessarily caused solely by carious lesions.24, 25

It is also necessary to discuss whether MIH represents an indicator ofa higher caries risk at the patient or at the tooth level. Not only can post-eruptive enamel breakdown lead to dentine exposure, but the rough and porous enamel surface typically present in hypomineralized enamel also makes effective cleaning challenging and facilitates plaque accumulation. Moreover, the hypomineralized enamel may be more susceptible to caries development due to its lower mineral content and consequently reduced resistance to the demineralizing effects of acids from a cariogenic biofilm. Indeed, it has been shown that MIH-affected molars with compromised enamel and dentine exposure are more susceptible to faster caries progression under a cariogenic biofilm.25 These biological and clinical characteristics support the hypothesis that MIH-affected teeth may be more vulnerable to caries development than unaffected teeth.26 Nevertheless, the available evidence is still limited by methodological challenges, particularly the difficulty in distinguishing carious lesions from post-eruptive enamel breakdown and MIH-related restorative treatment when conventional caries indices are used. Consequently, further longitudinal studies employing more specific diagnostic criteria are required to clarify whether MIH is associated with an increased risk of caries development and whether this association occurs primarily at the tooth rather than the patient level.

Key concepts for clinical management of MIH in molars

From a functional perspective, the clinical management of the first permanent molars is the most challenging aspect when treating patients with MIH. From non-invasive approaches aimed to prevent enamel breakdown to the management of severely affected molars, there is still limited evidence regarding the effectiveness of the available treatment options.

Evidence of clinical efficacy of available treatment options to prevent PEB and caries lesions

Ideally, the treatment for permanent molars with demarcated opacities is the prevention of PEB. In vitro and in vivo studies have demonstrated that hypomineralized enamel exposed to remineralization agents (toothpastes containing casein phosphopeptide and amorphous calcium phosphate - CPP-ACP or hydroxyapatite, and fluoride varnish) shows improvement in mineral content, mineral density, physical strength, or a decrease in laser fluorescence values.27, 28 However, considering that MIH lesions are subsurface in nature, originating at the amelodentinal junction and often covered by an apparently intact superficial layer, these findings may also represent post-eruptive maturation or superficial remineralization rather than true recovery of the underlying defect. This is likely why there is no clinical evidence that any remineralization agent prevents enamel disintegration in the context of MIH. Although microscopic superficial modification of hypomineralized enamel occurs following exposure to remineralization agents, it does not necessarily mean that the treated enamel becomes less susceptible to PEB.29 Nonetheless, the recommendation for daily use of fluoridated toothpaste (≥ 1,000 ppm F) remains undisputed due to its well-documented benefits in the control of dental caries.

The effectiveness of fissure sealants in preventing and controlling occlusal caries lesion in permanent teeth is well stablished.30 Considering that MIH-affected molars are more prone to caries, when the patient is at caries risk, fissure sealants are among the recommended preventive strategies.5 While resin-based sealants show significantly higher retention rates,31, 32 the caries preventive effect is similar between GIC and resin-based sealants.32 However, the high retention rate of resin-based sealants depends on optimal moisture control, what is not achievable during early stages of tooth eruption. Therefore, GIC sealants are frequently used in MIH-affected molars, particularly when they are not fully erupted.33

As sealants act as a physical barrier by isolating the surface of pit and fissures from the biofilm accumulation, they protect MIH-affected molars against caries; however, the same protective effect has not been observed for PEB.34 This can be explained by the fact that demarcated opacities are not confined to the areas covered by the sealant. Even when the sealant is fully retained in the pit and fissure areas, PEB may occur in cusps or other tooth surfaces not directly protected by the sealant. It should also not be expected that fluoride released by the GIC will reinforce the surrounding hypomineralized enamel sufficiently to prevent PEB.29

All demarcated opacities may be prone to post-eruptive breakdown (PEB) and should be monitored; however, as yellow brownish opacities are at higher risk of PEB than creamy-white ones,35 it is recommended to monitor patients with darker opacities at shorter intervals. PEB detected at early stages can be covered and protected with GIC or resin-based materials, thereby postponing more invasive procedures.

Evidence of clinical efficacy of available restorative treatment options for severe defects

The evidence to support restorative options for severely MIH-affected molars is still limited, primarily due to the considerable variability among the studies regarding study design, management of the surrounding hypomineralized enamel, criteria used to assess restoration success, and follow-up periods.28, 36

Nonetheless, with respect to direct restorations, composite resins have shown considerably higher success rates in medium- to long-term studies compared with glass ionomer cement (GIC) restorations.28, 36, 37 The success rate of GIC restorations has been reported to be as high as 86 to 98% in studies with follow-up limited to 18 months,38, 39, 40 but this drops to below 50% in studies with follow-up periods longer than 42 months.37, 41 In contrast, the success rate of composite resin restorations ranges from 70 to 74.5% after 42 months42 and reaches approximately 80% after 10 years.41 However, these findings should be interpreted with caution. Most conclusions regarding the superiority of composite resin over GIC are based on indirect comparisons across independent studies with different methodologies, follow-up periods, clinical settings, and outcome definitions. Direct evidence comparing both materials in MIH-affected teeth remains limited, with only a small number of randomized clinical trials available and inconsistent results reported.43, 44 Therefore, the current literature does not provide sufficient evidence to establish a clear consensus regarding the superiority of one material over the other. Further well-designed randomized clinical trials with long-term follow-up are needed to determine the most appropriate restorative material for MIH-affected teeth.

Across the studies, the influence of factors such as cavity size, cusp involvement, and stage of tooth eruption is often not considered in outcome analyses.37, 39, 40, 45, 46 Cusp involvement has been identified as the main reason for failure of composite resin restorations in both 12-month47 and 24-month follow-up studies.48

When indirect restorations are used, survival rates above 90% have been reported after three years or more, regardless of the material used (ceramic, resin, metal onlays or stainless-steel crowns - SSC).36, 41, 42, 49, 50, 51 Therefore, before indicating a direct restoration, it is advisable to assess whether PEB, in association or not with atypical caries, extends to multiple tooth surfaces and cusp areas. The higher failure rate of direct restorations compared with indirect restorations in MIH-affected molars may be related to inadequate indication of the restorative material or technique than the presence of hypomineralized enamel itself.52 One possible explanation for the superior survival rates reported for indirect restorations is that the hypomineralized enamel surrounding post-eruptive breakdown lesions is either removed during tooth preparation or subsequently protected by the restoration itself. This hypothesis is supported by recent findings showing that the longevity of composite restorations in MIH-affected teeth is significantly improved when residual hypomineralized enamel adjacent to the defect is removed before restoration placement compared with more conservative approaches that preserve such enamel.36 These findings suggest that restoration failure may be more closely related to the presence of unsupported or structurally compromised hypomineralized enamel at restoration margins than to the restorative material itself.36 However, the recommendation to routinely remove all remaining hypomineralized enamel should be interpreted with caution. In many MIH-affected teeth, demarcated opacities extend over large portions of the crown, and extensive removal of affected enamel may result in unnecessary loss of tooth structure, weakening of the remaining crown and earlier entry into the restorative cycle. Therefore, decisions regarding enamel removal should be individualized, balancing the potential benefits for restoration longevity against the principles of minimally invasive dentistry and long-term preservation of tooth structure.

In very young patients and in partially erupted molars, GIC may be indicated as a temporary protective filling until a long-term option can be provided.40 In such cases, when PEB extends to multiple surfaces, the use of an orthodontic band has been suggested to protect the GIC and enhance the longevity of the temporary filling.53

The highest survival rates have been reported for indirect laboratory-fabricated restorations.28, 36, 37, 49, 50 However, conventional indirect restorative procedures require more complex tooth preparation and a minimum stage of tooth eruption. In addition, they are more time-consuming and highly dependent on patient cooperation. Therefore, they are better indicated when the patient reaches adolescence or young adulthood.

Preformed SSC have also shown very high success rates48, 54, 55 and, more recently, have been proposed using a minimally invasive approach, without traditional tooth preparation.48, 56, 57 The use of SSC based on the Hall Technique principle,58 in which no tooth preparation is performed, has emerged as a promising strategy for severely affected molars, with PEB and/or atypical caries extending to multiple tooth surfaces and cusps. This approach is a non-invasive and practical procedure that may serve as either a temporary or longer-term protective restoration,52 although further clinical studies are still needed to support its widespread recommendation. Nevertheless, the application of this concept in MIH-affected molars may differ slightly from the original Hall Technique. In clinical practice, limited crown adjustments are frequently required to improve cervical adaptation and minimize occlusal discrepancies, allowing better fit and retention while still preserving the minimally invasive nature of the procedure.

Figure 2 presents a treatment decision tree for MIH-affected molars. Besides monitoring, desensitizing approach, sealants and restorations are among the treatment options.

Figure 2. Treatment decision tree for MIH-affected molars. Monitoring, desensitizing approach, sealants and restorations are presented as treatment options.

Evidence of clinical efficacy of timed extractions

Extraction may be the only option for severely affected molars where endodontic treatment and/or restoration is no longer feasible. Alternatively, extractions may be planned as a strategic approach for FPMs with poor medium- to long-term prognosis.28

The decision to extract severely affected FPM requires individual assessment and should take into account patient age, stage of development of the second molars, presence of third molars, as well as patient and parental expectations.59 In addition, the presence and type of malocclusion, facial pattern, space requirements, and overall orthodontic treatment objectives should be carefully evaluated, as these factors may substantially influence both the indication and timing of extraction.60 Therefore, treatment planning often requires close collaboration between pediatric dentists and orthodontists to ensure that the extraction decision is integrated into the patient’s overall occlusal and orthodontic management.

In patients without significant orthodontic concerns, extraction between 8 and 10 years ofage is generally considered the most favorable timing for spontaneous space closure.60 At this stage, the second permanent molar and premolar typically present early root development, usually with no more than one-third of the root formed, increasing the likelihood of favorable mesial migration and eruption of the second permanent molar into the position of the extracted FPM.56 However, when malocclusions are present, the optimal timing may differ from this recommendation and should be determined according to the individual orthodontic treatment plan. In some situations, delaying extraction may be advantageous, allowing the compromised FPM to be incorporated into a broader orthodontic strategy.60 Radiographic evaluation at this age may also provide useful information regarding the presence or absence of the developing third molar, which can contribute to long-term treatment planning. Moreover, a more favorable tooth migration is generally expected in the maxillary arch compared with the mandible.59, 60, 61, 62

Additionally, it is important to consider that extraction of FPM does not guarantee that the patient will have permanent molars free of enamel hypomineralization, because second permanent molars can also be affected by enamel hypomineralization.52, 63, 64, 65 Although they are typically less severely affected then FPM, they may still require restorative treatment and continuous monitoring.

Key concepts for clinical management of MIH in anterior teeth

Patients with severe MIH often report difficulties in eating, drinking, and daily activities, such as toothbrushing. These challenges are reflected in higher scores for negative impact on oral symptoms and functional limitations in questionnaires assessing oral health related quality of life (OHRQoL).66 However, when visible opacities are present in anterior teeth, a negative impact on psychosocial domain may also be observed67. Treatments aimed to “mask” or “disguise” opacities in anterior teeth have been shown to significantly improve the socio-emotional wellbeing and the self-perception of tooth appearance in children and adolescents.68, 69 Therefore, patients who report concerns and negative impact on their quality of life due to affected anterior teeth should be considered eligible for esthetic interventions.67

Minimally invasive options, such as tooth bleaching, microabrasion, resin infiltration, or combinations of these approaches, should be preferred.70 Each option follows a different mechanism: bleaching aims to reduce the color difference between whitish opacities and the surrounding sound enamel and reduce the intensity of yellow-brown opacities; microabrasion removes superficial discolorations while resin infiltration restores the refractive index of the affected enamel by filling subsurface porosities.71

For effective masking with resin infiltration, adequate penetration of the resin into hypomineralized enamel is essential. Factors such as the presence and thickness of the pseudo normal surface layer and the depth of the lesion influence the level of resin penetration.72 In most cases of hypomineralization, the more porous enamel is covered by a hypermineralized surface layer, and thus, the lesion is wider in the subsurface than at the surface. Acid etching, combined or not with microabrasion, may provide access to the central part of the lesion but not to its margins.73 In fact, it has been demonstrated that resin infiltration is optimized by increasing both etching time and resin application time.69 However, even more effective results have been achieved through cycles of selective removal of superficial enamel using a polishing bur combined with short acid etching.74 Transillumination during the ethanol rewetting phase of the technique is a valuable tool for detecting residual closed lesion areas. In this situation, the bur should be selectively used again until a complete access to the lesion body is achieved.74

At-home bleaching has been demonstrated to convert yellowish opacities into whitish ones and to reduce the color contrast between the opacity and the surrounding sound enamel by the overall tooth whitening.75 Therefore, it has been strongly recommended as a first step prior to resin infiltration.74, 75

In most cases, the microinvasive procedures are sufficient to achieve satisfactory masking of opacities. However, more complex cases may require restorative interventions. When removal of a thicker enamel layer is necessary to access deeper subsurface porosities, or when enamel breakdown is present, localized composite restorations may be require restoring the contour of the tooth surface.70, 75 Figure 3 presents a treatment decision tree for MIH-affected incisors. Besides monitoring, desensitizing approach, and microinvasive esthetic treatment are among the options.

Figure 3. Treatment decision tree for MIH-affected incisors. Monitoring, desensitizing approach, and microinvasive esthetic treatment are presented as options.

Key concepts for clinical management of hypersensitivity

Patients with MIH frequently report hypersensitivity during daily activities such as eating, toothbrushing, and inhalation of cold air.7 The prevalence of hypersensitivity ranges from 30 to 55% among patients with MIH, depending on the diagnostic method and the MIH severity.76 Although the exact mechanism leading to increased sensitivity in MIH-affected teeth is not fully understood, it appears to be related to the penetration of bacteria through enlarged interprismatic spaces, reaching the dentinal tubules and causing subclinical pulpal inflammation.77 Additionally, the highly porous enamel fails to adequately protect the underlying tissues from thermal, physical, and chemical external stimuli.78 In clinical practice, patients with MIH should be routinely asked about difficulties in daily activities such as consuming cold foods or drinks, toothbrushing, and chewing solid food.78

Occlusion of the enamel porosities is expected to relieve the symptoms associated to hypersensitivity. Desensitizing products, such as toothpastes containing 8% arginine and calcium carbonate,79 10% microcrystalline hydroxyapatite,80 or silicon combined with calcium, and a CPP-ACP mousse,81 have been shown to significantly reduce sensitivity in patients with MIH, as measured by the Schiff Cold Air Sensitivity Scale (SCASS) following cold and tactile stimuli. Sealants have also demonstrated a significant effect in reducing hypersensitivity in MIH-affected molars regardless ofwhether resin-based or GIC materials are used.82, 83, 84 SCASS scores shown to decrease significantly after a single application of silver diamine fluoride (SDF)85, 86, 87 with additional benefit observed when a GIC sealant was placed over SDF.85, 86 The desensitizing effect of fluoride varnish applied weekly for four weeks has been shown to be potentialized by two sessions of photobiomo dulation using a low-power diode laser.88 Similarly, low-power laser therapy has been reported to enhance the effect of GIC sealants in reducing hypersensitivity in first permanent molars.89

A recommended approach to manage hypersensitivity involves a two-phase strategy: an initial phase using low-power laser therapy, followed by a second phase aimed at creating a physical barrier against external stimuli. Low-power laser therapy is thought to inhibit sensory nerve activity and promote the release of neurotransmitters, resulting in an analgesic effect, while desensitizing agents act by occluding enamel porosities and dentinal tubules.78

Future perspectives

For many years, restorative failures in MIH-affected teeth have been primarily attributed to reduced adhesion to hypomineralized enamel, a concept largely derived from laboratory studies. 90 However, an important question remains unresolved: although bond strength to hypomineralized enamel may be reduced, is this reduction clinically sufficient to compromise restoration survival in vivo? This issue still requires further investigation. Based on the assumption that improved adhesion results in better restorative outcomes, some authors have advocated the removal of hypomineralized opacities surrounding PEB before restoration and reported higher survival rates following this approach.37 However, the benefits associated with opacity removal may not necessarily be explained by improved bonding alone. An alternative interpretation is that the residual hypomineralized enamel surrounding the restoration represents a structurally fragile substrate that remains susceptible to further post-eruptive breakdown. Consequently, what is often interpreted as restoration failure may, in some cases, reflect fracture of the surrounding enamel rather than loss of restoration retention itself. In this context, removal of the residual hypomineralized enamel may improve survival rates not only because it provides a more favorable bonding substrate, but also because it eliminates tissue that is inherently prone to future breakdown.

From this perspective, preserving and strengthening hypomineralized enamel rather than removing it may represent a more conservative and biologically oriented strategy. Current evidence suggests that conventional remineralizing agents and sealants are unable to substantially improve the mechanical properties of the defect.33, 34 Therefore, alternative approaches such as resin infiltration and enamel covering strategies have been proposed with the aim of reinforcing hypomineralized enamel and increasing its resistance to fracture.91 Future studies should determine whether these approaches are capable of effectively protecting MIH-affected enamel against post-eruptive breakdown. If proven effective, they could be implemented soon after tooth eruption to prevent hypomineralized enamel breakdown and reduce the future need for restorative intervention. In teeth that already present PEB, these strategies could also be combined with restorative procedures to protect residual hypomineralized enamel surrounding the restoration, thereby reducing the risk ofsubsequent enamel fracture. Additionally, these approaches may contribute to the management of hypersensitivity. By infiltrating or covering the porous hypomineralized enamel, these materials may reduce fluid movement and external stimuli transmission through the defect while simultaneously reinforcing the weakened enamel structure. Consequently, they have the potential to provide a dual benefit by both increasing resistance to post-eruptive breakdown and alleviating one of the most common and clinically relevant symptoms associated with MIH.

In addition to these considerations, another important aspect concerns to the current nomenclature of MIH, which may no longer fully reflect the true extent and clinical variability of the condition. Although the term implies that the defect is limited to first permanent molars and permanent incisors, a growing body of evidence demonstrates that hypomineralization may also affect second permanent molars, premolars, permanent canines, and primary teeth, particularly second primary molars and primary canines. Furthermore, numerous studies indicate that MIH and hypomineralized second primary molars (HSPM) are not distinct disorders but rather different manifestations within a broader spectrum of developmental enamel hypomineralization. Collectively, these findings suggest that the current terminology may be overly restrictive and no longer fully representative of the clinical reality. Consequently, it may be timely to reconsider the nomenclature and adopt a more comprehensive and inclusive term that better reflects the diversity of affected teeth, improves diagnostic consistency, and facilitates the development of preventive and therapeutic strategies across the full spectrum of enamel hypomineralization defects.92

Data availability:

The authors declare that all data generated or analyzed during this study are included in this published article.