Birgitta Jälevik

Molar-incisor hypomineralisation

Molar Incisor Hypomineralisation (mih) wordt omschreven als een hypomineralisatie (van systemische oorsprong) van een tot vier blijvende eerste molaren, vaak in combinatie met aangedane incisieven. mih-molaren zijn fragieler en cariesgevoeliger dan gewone molaren. Een kenmerk van mih-molaren is een extreme overgevoeligheid voor koude, warmte en/of lucht. De behandeling van deze molaren kan de behandelaar soms voor klinische problemen stellen. Het aantal gevallen van mih verschilt per land en per geboortejaar en varieren tussen de 3,6% en 25%. De oorzaak van mih is nog niet duidelijk. Wel duidelijk is dat het moet ontstaan in de periode van maturatie van het glazuur, dus tijdens de eerste levensjaren van het kind. Zolang de oorzaken van mih nog niet bekend zijn, is het verstandig om kinderen die in hun eerste levensjaren vaak ziek zijn geweest, kinderen met hypomineralisatie van de 2e melkmolaren en kinderen die op de blijvende incisieven duidelijk begrensde opaciteiten vertonen, tijdens de eerste wisselfase regelmatig te controleren om op tijd eventuele mih te signaleren.

The prevalence of demarcated opacities in permanent first molars in a group of Swedish children

The permanent teeth of 516 7- and 8-year-old Swedish children from a low-fluoride area were examined for developmental enamel defects. Special attention was paid to demarcated opacities in permanent first molars and permanent incisors (MIH). The examination was done in their schools, using a portable light, a mirror, and a probe. The modified DDE index of 1992 was used for recording the enamel defects, supplemented with a further classification into severe, moderate, and mild defects. Demarcated opacities in permanent first molars were present in 18.4% of the children. The mean number of hypomineralized teeth of the affected children was 3.2 (standard deviation, 1.8), of which 2.4 were first molars. Of the children 6.5% had severe defects, 5% had moderate defects, whereas 7% had only mildly hypomineralized teeth. In conclusion, hypomineralized first molars appeared to be common and require considerable treatment in the Swedish child population.

Best Clinical Practice Guidance for clinicians dealing with children presenting with Molar-Incisor-Hypomineralisation (MIH)

BACKGROUND: The European Academy of Paediatric Dentistry (EAPD) has long recognised the necessity of promoting further research and knowledge regarding the dental defect described as molar-incisor-hypomineralisation (MIH). Following the establishment by EAPD of the defect diagnostic criteria in 2003, the publication of various papers and a whole issue assigned to the defect in the European Archives of Paediatric Dentistry (2008), an Interim Seminar and Workshop on MIH was organized in Helsinki in 2009. RESULT: The outcome of this event is the present consensus paper on the prevalence, diagnosis, aetiology and treatment for children and adolescents presenting with MIH. A clear diagnostic proposal and a treatment decision-making guide are presented together with suggestions on aetiology and guidance forfuture research. CONCLUSION: MIH is an important clinical problem that often concerns both the general dental and specialist paediatric dentists; the present ‘best clinical practice guidance’ aims to further help clinicians dealing with the condition.

Secondary ion mass spectrometry and X-ray microanalysis of hypomineralized enamel in human permanent first molars

A common finding in Swedish children is hypomineralization in first molars of unknown cause. Little is known about the chemical composition of the disturbed enamel. The aim here was to analyse the concentration gradients for F, Cl, Na, Mg, K and Sr in hypomineralized enamel from 17 permanent molars by means of secondary ion mass spectrometry, to complete this analysis with an examination of the main matrix elements O, P and Ca by means of X-ray microanalysis, and to compare them with normal enamel. Hypomineralized enamel had a higher content of carbon and the calcium as well as the phosphorus concentration was lower than in normal enamel. The mean Ca/P ratio in hypomineralized areas was significantly lower (1.4) than in the adjacent normal enamel (1.8). The F content was highly variable in impaired enamel and higher than in normal, but close to the surface there was most often no difference between the two. Contents of Mg and K were slightly higher in hypomineralized areas, especially towards the surface. Also Na had a somewhat higher content toward the surface in defective enamel. Cl and Sr contents had negligible or no diversity in relation to the degree of mineralization.

Chemical, mechanical and morphological properties of hypomineralized enamel of permanent first molars

Abstract Objective. The microstructure of hypomineralized enamel in permanent teeth has been described in several studies as less distinct prism sheaths and disorganized enamel with lack of organization of the enamel crystals. The mechanical properties, hardness and modulus of elasticity of the hypomineralized enamel have lower values compared with normal. The aim of this study was to examine normal and hypomineralized enamel using scanning electron microscopy (SEM), hardness measurements and X-ray microanalysis (XRMA). Material and methods. Four extracted hypomineralized permanent first molars, sectioned and cut in half, were analyzed with SEM, XRMA and hardness measurements. Results. An inverse relation was found between the micro hardness and the Ca:C ratio in hypomineralized and normal enamel. The acid-etched hypomineralized enamel appeared on SEM to be covered with a structureless layer and the prisms appeared disorganized, with thick prism sheaths and loosely packed crystallites. Furthermore, bacteria were found deep in porous hypomineralized enamel close to the enamel–dentin junction. Conclusions. Teeth diagnosed with molar incisor hypomineralization have significantly lower hardness values in the hypomineralized enamel compared with normal enamel. The hardness values vary according to the morphological and chemical properties.