The prevalence and characteristics of and the association between MIH and HSPM in South-Western France.

BACKGROUND: Molar-incisor hypomineralisation (MIH) and hypomineralised second primary molars (HSPM) involve qualitative structural developmental anomalies of tooth enamel, affecting the first permanent molars (FPM) and the second primary molars, respectively. This developmental anomaly of systemic origin has important consequences for oral health. AIM: To determine the prevalence of MIH and HSPM in south-western France and explore the distribution of hypomineralised lesions on permanent and primary molars. DESIGN: Amongst 856 children (aged 7-9 years) in schools randomly selected by the Academy of Bordeaux (Ministry of Education), the FPM, permanent incisors and the second primary molars were examined by two examiners trained and calibrated for the diagnostic criteria for MIH and HSPM of the European Academy of Paediatric Dentistry. RESULTS: Molar-incisor hypomineralisation was present in 160 children (18.7%) and HSPM in 81 children (9.5%); 4.9% had both HSPM and MIH (42 of 856). Hypomineralised lesions were present in 1-4 FPM in affected individuals (mean = 2.4) and were distributed in an asymmetrical manner with widely varying severity at the tooth and individual level. A child with HSPM was more likely to have MIH than a child without HSPM (95% CI OR = 6.0 [3.7-9.7]; p < .0001). CONCLUSION: Molar-incisor hypomineralisation and HSPM have three main asymmetrical characteristics: tooth location, severity of hypomineralisation and number of teeth affected.

What do we currently need to know about molar incisor hypomineralisation (MIH) and hypomineralized second primary molars (HSPM)? / Que faut-il savoir, à l'heure actuelle, sur les hypominéralisations molaires incisives (MIH) et les hypominéralisations des secondes molaires temporaires (HSPM) ?

Introduction: Molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM) are qualitative and asymmetric enamel defects. MIH affect at least one permanent first molar and can also be associated with permanent incisors. HSPM affect at least one primary second molar and possibly primary canines. Hypomineralized enamel is characteristic: the enamel prisms are disorganized, less distinct, the interprismatic space is more marked, the mineral density is decreased and the protein content is increased. Currently, etiologies remain unknown but the various studies tend towards a multifactorial model with several systemic, genetic and/or epigenetic factors, acting in a synergistic or additive way. Material and Method: The authors highlight the various factors involved in diagnosing MIH and HSPM. A review of the prevalence (French and worldwide) and etiologies of these pathologies is also provided, to enable practitioners to answer any questions parents may have. Conclusion: The knowledge of these different elements on diagnosis, structure, prevalence and etiologies will allow the orthodontist to better collaborate with the dentist but also with the parents in order to ensure an adequate dental and orthodontic management.

Introduction: L'hypominéralisation molaire incisive (MIH) et l'hypominéralisation des secondes molaires temporaires (HSPM) sont des défauts qualitatifs et asymétriques de l'émail. Les MIH affectent au moins une première molaire permanente et peuvent également être associées aux incisives permanentes. Les HSPM affectent au moins une deuxième molaire temporaire et éventuellement les canines temporaires. L'émail hypominéralisé est caractéristique : les prismes d'émail sont désorganisés, moins distincts, l'espace interprismatique est plus marqué, la densité minérale est diminuée et la teneur en protéines augmentée. Actuellement, les étiologies restent méconnues mais les différentes études tendent vers un modèle multifactoriel avec plusieurs facteurs systémiques, génétiques et/ou épigénétiques, agissant de manière synergique ou additive. Matériel et méthode: Les auteurs mettent en avant les différents éléments permettant le diagnostic des MIH et des HSPM. Un point sur les prévalences (française et mondiale) et sur les étiologies de ces pathologies est également proposé afin de permettre aux praticiens de répondre aux éventuelles interrogations des parents. Conclusion: La connaissance de ces différents éléments sur le diagnostic, la structure, les prévalences et les étiologies permettra à l'orthodontiste une meilleure collaboration avec le chirurgien-dentiste, mais également avec les parents afin d'assurer une prise en charge dentaire et orthodontique adéquate.