The term molar incisor
hypomineralization (MIH) was introduced in 2001 to describe the clinical
appearance of enamel hypomineralization of systemic origin affecting one or
more permanent first molars (PFMs) that are associated frequently with affected
incisors. The condition is attributed to disrupted ameloblastic function during
the transitional and maturational stages of amelogenesis. This condition is
recognized in various terms such as hypomineralized PFMs, idiopathic enamel
hypomineralization , dysmineralized PFMs, nonfluoride hypomineralization and
cheese molars.
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| Molar incisor hypomineralization |
Epidemiology
The prevalence data for MIH are
limited due to various diagnostic classifications. According to existing data
the prevalence ranges from 4% to 25% across different populations. The number
of hypomineralized PFMs in an individual can vary from 1 to 4, affecting
particularly 2 or more molars including the contralateral tooth, where the
teeth are moderately or severely affected. The risk of involvement of the
permanent maxillary incisors appears to increase when more PFMs are affected.
Putative factors associated with
disrupted amelogenesis of PFMs include systemic conditions and environmental
insults influencing natal and early development specially during the child’s
first 3 years. The systemic conditions
implicated to date include nutritional deficiencies, brain injury and
neurologic defects, cystic fibrosis, syndromes of epilepsy and dementia
(Kohlschutter-Tonz syndrome), nephrotic syndrome, atopia, lead poisoning,
repaired cleft lip and palate, radiation treatment, rubella embryopathy,
epidermolysis bullosa, ophthalmic conditions, celiac disease, and
gastrointestinal disorders. Conditions common in the first 3 years, such as upper
respiratory diseases, asthma, otitis media, tonsillitis, chicken pox, measles,
and rubella, are also known to be associated with MIH. Some studies suggest the
association of Preterm birth with increased prevalence of enamel defects,
including hypomineralization and hypoplasia in the permanent dentition.
Clinical presentation and Diagnosis
Criteria for the diagnosis of
demarcated opacities, post-eruption breakdown (PEB), atypical restorations, and
extracted PFMs due to MIH were developed by Weerheijm et al. Dentitions with generalized opacities present on
all teeth rather than limited to the PFMs and permanent incisors, are not
considered to have MIH.
Four PFMs
and 8 erupted permanent incisors are examined wet for demarcated opacities (white-cream
or yellow-brown in color, of normal thickness with a smooth surface), post
eruptive breakdown, and atypical restorations.
·
The opacities are usually limited to the incisal or cuspal one
third of the crown, rarely involving the cervical one third.
·
Due to the unusual size and shape, restorations may not conform to
typical caries patterns and frequently involve the cuspal or incisal one third
of the crown.
·
Enamel opacities may occur adjacent to restoration margins.
Diagnostic Categories of
MIH
·
Mild MIH
o
Demarcated opacities are in
nonstress-bearing areas of the molar
o
No enamel loss from fracturing is present
in opaque areas
o
There is no history of dental
hypersensitivity
o
There are no caries associated with the
affected enamel
o
Incisor involvement is usually mild if
present
·
Moderate MIH
o
Atypical restorations can be present
o
Demarcated opacities are present on occlusal/incisal
third of teeth without posteruptive enamel breakdown
o
Posteruptive enamel breakdown/caries are
limited to 1 or 2 surfaces without cuspal involvement
o
Dental sensitivity is generally reported
as normal
·
Severe MIH
o
Posteruptive enamel breakdown is present
o
There is a history of dental sensitivity
o
Caries is associated with the affected
enamel
o
Crown destruction can advance to pulpal
involvement
o
Defective atypical restoration
o
Aesthetic concerns are expressed by the
patient or parent
Differential Diagnosis
Fluorosis
Amelogenesis imperfecta
Enamel hypoplasia
o
It can be differentiated from fluorosis as
its opacities are demarcated, unlike the diffuse opacities that are typical of
fluorosis. Fluorosis is caries resistant and MIH is caries prone and also fluorosis can be related to a period in which the fluoride intake was
too high
o
Choosing between amelogenesis imperfecta
(AI) and MIH: only in very severe MIH cases, the molars are equally affected and mimic
the appearance of AI
o
In MIH, the appearance of the defects will
be more asymmetrical and in AI, the molars may also appear taurodont on radiograph and there is
often a family history.
Management
MIH’s clinical
management is challenging due to:
1. The sensitivity and rapid development of dental caries in
affected PFMs
2. The limited cooperation of a young child
3. Difficulty in achieving anesthesia
4. The repeated marginal breakdown of restorations.
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| Management of Molar incisor hypomineralization |
