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BSPD Specialists’ meeting, Leeds, 14 th March 2003
Molar-Incisor Hypoplasia Prevalence and Histology.
Karin Weerheijm
Dept of Cariology, Endodontology, Pedodontology Academic Centre for Dentistry
(ACTA), Amsterdam.
Proposed definition = Hypomineralisation of systemic origin of 1-4 permanent first
molars, frequently associated with affected incisors.
(c.f. Weerheijm KL, et al. Caries Res 2001; 35: 390-391).
Observations:
Some teeth affected by MIH exhibit significant sub-surface porosity. This results
in breakdown of the enamel.
Primary teeth are not affected.
Presentation may be asymmetrical.
Affected teeth are sensitive, even if the enamel has not broken away.
The cause of the increased sensitivity is not yet known.
The prevalence is equal in the upper and lower jaws
(c.f. Weerheijm KL, et al. J Dent Child 2001; 68: 259-262).
It is not known if there is a racial difference.
It is not known if the tips of the permanent canines are affected.
Affected enamel exhibits increased carbon content, and decreased calcium and
phosphorus concentrations (Jälevik, et al. Arch Oral Biol 2001; 46: 239-247).
In fluorosis, enamel is caries resistant. In MIH, affected teeth are more caries
susceptible, and post-eruptive breakdown occurs. The condition may be
misdiagnosed as hypoplasia.
Problems associated with MIH:
Caries development
Post-eruptive enamel breakdown is unpredictable
Anaesthesia
Prevalence of MIH: Ranges 4 – 25% (prevalence data are limited).
Aetiology of MIH:
Multifactorial
Ameloblasts are affected at the late secretory or early maturation stage.
Some ameloblasts are irreversibly damaged, resulting in yellow-brown opacities,
and more porosities.
Where ameloblasts have recovered, white opacities result.
Cosmetic management of anterior teeth with MIH
Stephen Fayle, Consultant in Paediatric Dentistry, Leeds Dental Institute.
Treatment options for opacities:
Microabrasion Better suited to diffuse opacities
Defects in MIH are usually full-thickness
Carbamide peroxide bleaching Lightens the whole tooth, making the
opacity less obvious, but doesn’t affect
the opacity.
Direct and indirect veneers
Aesthetic composites
Esthetex (Dentsply)
Cosmodent real enamel system (v.expensive)
Polishing systems
Enhance (Dentsply)
Soflex (3M)
Prisma gloss
Problems and restorative options for first permanent molars with MIH
Stephen Fayle
Analgesia can be a problem in MIH.
The phenomenon of tachyphylaxis has been observed (LA has taken effect, but
once it wears off, subsequent analgesia is difficult to achieve).
Special techniques of analgesia may be required:
Intra-ligamental
Maxillary molar block (c.f. Adatia 1966) – after-pain may be a problem due to
decreased blood supply caused by vasoconstriction
Palatal analgesia is required
Computerised analgesia (“the wand”) may prove useful (c.f. Allen et al. Paed
Dent 2002; 24: 315-320. Gibson et al. Paed Dent 2000; 22: 458-462. Ram et al.
Int J Paed Dent 2002: 12: 80-89).
Desensitising agents:
Fluoride varnish – According to Stephen Fayle, Colgate Fluorogard Gel-Kam
works well in MIH (0.4% SnF).
Desensitising toothpastes
Bonding agents (hydrophilic recommended). In a study by Stephen Fayle, “Prime
& Bond” didn’t work.
Fissure sealants – glass ionomer based FSs may prove useful in MIH.
