Molar-incisor hypomineralization: an umbrella review

Objective: In recent years, Molar Incisor Hypomineralization (MIH) has become a subject that concerns the Paediatric Dentistry Community. The aim of the present umbrella review was to analyse previously published systematic reviews (SRs) on MIH in children and adolescents. Methods: Electronic database search was conducted (including PubMed, Embase, Scopus, Cochrane, Web of Science, and LILACS) until July 2020. Studies were included, if they were SR on MIH in children and adolescents. The methodological quality of SRs was judged by use of the MeaSurement Tool to Assess systematic Reviews 2. The primary outcomes included prevalence, aetiology, and clinical management of MIH. Data extraction and methodological quality assessment were performed. Results: Eighteen systematic reviews were included for data extraction. Among these, two were focussing on prevalence, five addressed aetiology, one highlighted the mechanical and chemical characteristics of enamel in MIH, one underlined the association between MIH and dental caries, six addressed the treatment, and one focussed on hypomineralization of primary teeth as a predictor of MIH. The results showed a high worldwide prevalence of MIH and an unknown aetiology of MIH, but reporting that the aetiology is most likely multifactorial. Different treatment approaches used were desensitizing and remineralizing products, resin infiltration, fissure sealant, atraumatic restorative treatment, resin composite restoration, and stainless steel crown (SSC), but also extraction associated with orthodontic treatment of the permanent first molars (PFMs) was reported on. The AMSTAR criteria 2 was applied, where six studies were assessed as having critically low quality, two studies as having low quality, and nine studies as having moderate quality. Conclusions: MIH is highly prevalent worldwide and has most likely a multifactorial aetiology. Different treatment approaches according to the degree of severity of lesion(s) are reported on. The quality of evidence produced by the available SRs was not favourable. More well-designed clinical trials and high standard systematic reviews are necessary to elucidate better MIH characteristics and treatment outcomes.