Molar-incisor hypomineralisation (MIH) is a common developmental condition which potentially affects 1 in 8 children.(1) It is important the dental team are aware of the signs and symptoms of this condition to ensure early diagnosis and effective management.
Molar-incisor hypomineralization (MIH) is a common developmental condition that potentially affects 1 in 8 children. (1) It is important the dental team is aware of the signs and symptoms of this condition to ensure early diagnosis and effective management.
The term MIH was first introduced in 2001 by Weerheijm et al. and is defined as hypomineralization of systemic origin, presenting as demarcated, qualitative defects of the enamel of one to four first permanent molars frequently associated with affected incisors. (2)
Epidemiological studies have shown a wide variation of between 2.8 and 40.2%. (3) This variation may be due to a lack of standardization in the tools used to record MIH, leading in many cases to an underestimation in prevalence. As a result, a recent systematic review and meta-analysis of MIH were carried out to provide a global prevalence which is estimated at 13.5%. (4)
Although the etiology of MIH is not fully understood, the general consensus highlights multifactorial risk factors concerning a disturbance in the enamel development during its maturation phase, due to interruption to the formation of ameloblasts. Risk factors include pre, peri, and postnatal issues, environmental conditions, and early childhood illness from a variety of diseases occurring in a child’s early life which can cause a disturbance in tooth development. (4)
Diagnosis
Determining a definitive diagnosis of MIH can be a challenge, especially in young children whose permanent dentition has not fully erupted so enamel defects will not be evident. Differential diagnoses should also be considered including amelogenesis imperfecta and dental fluorosis. Diagnosis of MIH should be made as soon as it is clinically apparent in both primary and permanent teeth. The child should be examined with clean wet teeth and if clinical signs exist, parents should be asked about any illness which occurred pre, peri, or postnatally or during the first three years of life. To help standardize diagnosis, the European Academy of Pediatric Dentistry (EAPD) published a policy document on the best clinical practice for clinicians dealing with children presenting with MIH. This includes diagnostic criteria of MIH reinforcing the use of specific clinical signs and symptoms. (5)
EAPD Diagnostic criteria of MIH (adopted from Weerheijm et al 2003; Lygidakie et al. 2010) (5)
Diagnostic feature
Description of the defect
Teeth involved
One to all four permanent first molars (FPM) with enamel Hypomineralization.
Simultaneously, the permanent incisors can be affected.
At least one FPM has to be affected for a diagnosis of MIH.
The more affected the molars, the more incisors involved and the more severe the defects.
The defects may also be seen at the second primary molars, premolars, second permanent molars, and the tip of the canines
Demarcated opacities
Clearly demarcated opacities present an alteration in the translucency of the enamel.
Variability in color, size, and shape.
White, creamy, or yellow to brownish color.
Only defects greater than 1 mm should be considered.
Post-eruptive enamel breakdown
Severely affected enamel breaks down following tooth eruption, due to masticatory forces.
Loss of the initially formed surface and variable degree of porosity of the remaining hypo-mineralized areas.
The loss is often associated with a pre-existing demarcated opacity.
Areas of exposed dentine and subsequent caries development.
Sensitivity
Affected teeth frequently reveal sensitivity, ranging from mild response to external stimuli to spontaneous hypersensitivity.
MIH molars may be difficult to anesthetize.
Atypical restorations
The size and shape of restorations are not conforming to the typical caries picture.
In molars, the restorations are extended to the buccal or palatal/lingual smooth surface.
Opacity can be frequently noticed at the margins of the restorations.
First permanent molars and incisors with restorations having similar extensions as MIH opacities are recommended to be judged as that.
Extraction of molars due to MIH
Extracted teeth can be defined as having MIH when there are: – Relevant notes in the records – Demarcated opacities or atypical restorations on the other first molars – Typically demarcated opacities in the incisors
The absence of early intervention can lead to a progressive breakdown of the tooth, increased risk of caries, possible pulpal inflammation, and hypersensitivity. Associated opacities on anterior teeth are less likely to have functional problems but may result in cosmetic and psychosocial issues. (6) The consequences of this can impact the function, social interaction, and quality of life of the patient.
Management
MIH presents a variety of challenges for the dental team. Younger patients may demonstrate higher levels of dental anxiety which can be exacerbated due to teeth being hypersensitive to thermal and mechanical stimuli. Teeth affected by MIH can also be difficult to anesthetize impacting the quality of restorative treatment and behavioral management. Septodont can aid patient management with our portfolio of world-leading dental pain management products, including the highest-quality pre-injection topicals, injectable anesthetics, and lower-deflection needles.
Management of MIH is largely informed by best-practice clinical guidelines. The International Association of Pediatric Dentistry (IAPD) has published consensus recommendations for the management of MIH(7) which include the following steps:
Early diagnosis allows the provision of preventive or early restorative intervention in order to avoid progressive breakdown and possible pulpal inflammation and hypersensitivity.
Restorations in MIH-affected teeth are associated with poorer long-term outcomes than those in unaffected teeth.
Long-term treatment concepts include a decrease in hypersensitivity, remineralization, sealants, resin infiltration, micro-abrasion, composites, amalgams, veneers, and crowns.
Hypersensitivity may be managed by desensitizing paste and fluoride varnish.
MIH-affected enamel may have compromised bonding for sealants and composites. For adhesive restorations, the cavity preparation should extend into hard tissue for better adhesion.
Amalgam restorations show high failure rates in atypically shaped molar MIH preparations. The need for retentive cavity preparations might aggravate existing tooth substance defects.
Glass ionomer cements have a high failure rate in MIH but may be used for the temporization of teeth. (7)
For mild cases of MIH in incisors, a combination of etching, bleaching, and sealing of affected areas may be a conservative approach. For more severe cases, micro-abrasion or composite may improve aesthetics. For severe cases of MIH in molars, full-coverage crowns may be necessary for maintenance.
Additional local anesthetic procedures may be necessary to manage hypersensitivity during restorative procedures.
Tooth extractions of the first permanent molars with or without subsequent orthodontic alignment may be considered before the eruption of the second permanent molars when more than one tooth is affected with severe MIH and pain, considering the patient’s dental age (preferably 8-9 years old), and the occlusion and status of the neighboring teeth.
Frequent recalls should be established for these patients, due to the high failure rate of the restorations in order to avoid secondary caries and more extensive breakdowns.
In addition to these recommendations, Biodentine® is used by some clinicians for indirect pulp capping or direct pulp capping when they manage the restoration of permanent molars severely affected.
Families are now returning for routine examination and with the potential of 1 in 8 children being affected by MIH, why not take this opportunity to share this information with your wider dental team? The implementation of a team approach to early diagnosis and appropriate management will minimize the impact of MIH on both the patient and the practice.
(3) Ghanim, A., Silva, M.J., Elfrink, M.E.C., et al. Molar incisor hypomineralization (MIH) training manual for clinical field surveys and practice. Eur Arch Pediatric Dent 18, 225–242 (2017). https://doi.org/10.1007/s40368-017-0293-9
(4) Lopes, L.B., Machado, V., Mascarenhas, P. et al. The prevalence of molar-incisor hypomineralization: a systematic review and meta-analysis. Sci Rep 11, 22405 (2021). https://doi.org/10.1038/s41598-021-01541-7
(5) Lygidakie et al (2010), Best clinical practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralization (MIH): an updated European Academy of Pediatric Dentistry policy document. European Archives of Pediatric Dentistry. https://link.springer.com/article/10.1007/s40368-021-00668-5
(6) Rodd, H.D et al (2022), Molar incisor hypomineralization: current knowledge and practice. Int Dent J. https://doi.org/10.1111/idj.12624
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