Exploring the association between genetic and environmental factors and molar incisor hypomineralization: evidence from a twin study

Prevalence of molar incisor hypomineralisation and associated factors amongst 8-year-olds in Ireland

PURPOSE

To describe the prevalence of molar incisor hypomineralisation (MIH) and a selection of potentially associated factors amongst 8-year-olds in Ireland.

METHODS

This study reports cross-sectional data from the Fluoride and Caring for Children's Teeth (FACCT) study 2017. Eight-year-olds in Dublin (n = 786) and Cork-Kerry (n = 1524) were clinically examined for MIH (EAPD criteria) and dental caries (DMFT). The association between potential aetiological factors and MIH was assessed using multivariable logistic regression. Potential effects of MIH on dental caries, oral health-related quality of life (OHRQoL) and parental perceptions of the appearance of their child's permanent incisors were investigated.

RESULTS

MIH prevalence was 11% in Dublin and 9% in Cork-Kerry. In Dublin, prevalence of MIH was higher amongst children who had health problems in the past year. There was no association between community water fluoridation and MIH in Cork-Kerry. In both regions, dental caries was higher amongst children with MIH. Parents of children with MIH in Dublin and Cork-Kerry were more likely to have noticed marks on their child's permanent incisors. In Dublin, MIH was associated with poorer parent-reported OHRQoL. Parents of children with MIH in Cork-Kerry were less likely to be satisfied with the colour of their child's permanent incisors.

CONCLUSIONS

MIH prevalence was 9-11%. The association between MIH and dental caries suggests that MIH severity in Ireland may be high. There is an urgent need for national data on MIH prevalence and severity, early identification of children with MIH and provision of preventive and treatment services in line with international best practise.

Ribbon-like hypomineralization in human dental enamel

Human dental enamel is a uniquely hard and tough biological realization of the inherently brittle apatite crystal. In sound enamel both structure and chemistry are organically fine-tuned, while developmental disorders - such as hypomineralization - often lead to severe enamel alterations resulting in weaker mechanical performance and shorter lifetime as in case of molar-incisor hypomineralization (MIH) which has a global prevalence of 13.5 %. However, causes of the development of hypomineralization disorder remain unclear up to date. In the present paper, a new form of dental hypomineralization is reported for the first time. Structural and chemical alterations of dental enamel exhibiting a special ribbon-like hypomineralization (RLH) are compared to the characteristics of sound and MIH-affected teeth. Microporosity, mineral density and characteristic 3D macroscopic shape of the RLH affected volumes were captured by micro-CT analysis. On the submicron-scale, nanoporosity, unusual morphologies and reduced size of apatite nanocrystals have been revealed. These RLH specific features are coupled with a particular chemical fingerprint in Raman spectroscopy, which allows its clear separation from MIH affected and sound enamel. Based on these nanostructural features we conclude different failure mechanisms in the biochemical control during crystallization of the RLH and MIH enamel. STATEMENT OF SIGNIFICANCE: Molar-incisor hypomineralization (MIH) is a developmental enamel disorder with up to 14 % prevalence, characterized by reduced mineral content, hypersensitivity, and post-eruptive enamel breakdown. The causes of the development of this disorder remain unclear up to date. In this study, we examine molars with hypomineralization in a ribbon-like macroscopic morphology. These molars show increased porosity, organic content, and reduced mineral content, while carbonate levels remain unchanged in both affected and unaffected areas, unlike MIH-affected enamel. Ribbon-like hypomineralized (RLH) enamel also features unusual apatite nanocrystal morphologies, including isometric crystals in the prism boundary zone and bean-shaped crystals with a soft central zone. Nanoscale analysis reveals RLH as a developmental anomaly distinct from MIH, offering novel insights into the biochemical controls of hypomineralization.

Knowledge, assessment and treatment of molar incisor hypomineralisation (MIH) among German dentists

OBJECTIVES

This study investigated the knowledge, perceptions, and clinical practices of German dentists regarding molar incisor hypomineralisation (MIH), a significant issue in paediatric dentistry. To date, no study has examined the knowledge and experience of German dentists with MIH.

SUBJECTS AND METHODS

A digital questionnaire comprising 25 items was designed to assess German dentists' understanding of MIH. The questionnaire was available online via Survio.de from March to June 2023. The responses were entered anonymously into an Excel spreadsheet and analysed using SPSS 29.0.

RESULTS

625 dentists were surveyed, and 517 questionnaires were evaluated. 99.2% of respondents treated patients with MIH, and 92.5% considered it a significant clinical problem. Commonly observed clinical presentations included yellow/brown defects (81%), enamel loss (46%) and white defects (36.4%). 68.6% of respondents noted an increase in MIH prevalence. Treatment barriers included child behaviour (44.7%), difficulties with local anaesthesia (22.7%), and extended treatment duration (15.3%). Most dentists (77.8%) expressed a desire for further training on MIH.

CONCLUSIONS

The data indicated that dentists' MIH management was influenced by specialisation and diagnostic confidence. Despite basic knowledge and experience, many respondents expressed a need for further education. Age-related biases and limited awareness of new techniques highlight the need for further research.

CLINICAL RELEVANCE

Dentists must receive comprehensive training to enable them to diagnose and treat patients promptly. This should include the development of updated courses, which should be aligned with international guidelines.

Frequencies of enamel hypomineralisation in permanent and primary molars in a medieval and early-modern-age population (7th - 17th c.) in Sains-en-Gohelle (Pas de Calais, France)

Molar Incisor Hypomineralisation (MIH) is defined as a qualitative demarcated enamel hypomineralisation defect of tooth enamel affecting at least one first permanent molar (FPM), often affecting permanent incisors. More recently, the term Hypomineralised Second Primary Molar (HSPM) was used to describe similar defects affecting second primary molars. Our observational study aimed at determining HSPM and MIH frequencies in a medieval and early-modern-age population population (Sains-en-Gohelle, France, 7th - 17th centuries) and compare it to the current worldwide and French prevalence values. To date, there are no other studies on this subject in France. European studies have been published, but the diagnosis of these pathologies is based solely on a visual examination. Our study differs from others by using objective diagnostic. microtomography and X-ray fluorescence. The use of these diagnostic methods allows differentiation between hypomineralised and taphonomic lesions. The frequencies of MIH and HSPM were, respectively, 12.3% and 13.3%. In fact, there were 10 individuals with at least one first permanent molar affected by MIH amongst the 81 individuals with at least one first permanent molar present, and 15 individuals with at least one second primary molar affected by HSPM among the 113 individuals with at least one second primary molar present.The presence of MIH and HSPM in ancient populations with frequencies respectively equivalent and higher than current worldwide averages renews the debate and questioning about the aetiological factors of these pathologies.

Current Knowledge of the Etiology and Management of Molar Incisor Hypomineralization in Children: A Narrative Review

Molar incisor hypomineralization (MIH) is a developmental condition affecting the enamel, primarily targeting one to four permanent first molars, often with the involvement of permanent incisors. The condition is characterized by distinct white-yellow or yellow-brown opacities, with more severe cases exhibiting hypomineralized enamel that is prone to breakdown. Recent data highlights MIH as a widespread dental issue seen across the globe. Despite its prevalence, the exact etiology remains unclear due to the variety of potential contributing factors. Managing MIH is particularly challenging, requiring a holistic approach to address the broad spectrum of symptoms and the heightened sensitivity of the affected teeth. Given the unique challenges of MIH, it is essential to gather updated and thorough knowledge. This understanding is critical for exploring potential preventive measures and enhancing treatment outcomes. This review aimed to examine the underlying causes of MIH, assess various treatment strategies, and offer a thorough understanding of the condition based on the latest research.

Influence of maternal health status during pregnancy and the child´s medical history on molar-incisor hypomineralization in a group of Spanish children (aged 6-14 years): a retrospective case-control study

BACKGROUND

Molar-incisor hypomineralization (MIH) is a qualitative enamel defect that is highly prevalent in children. It has been reported that patients with MIH have higher caries occurrence with an increased need and frequency of dental treatment compared to patients without MIH. The objective of this study was to analyze the association between MIH and a series of factors related to maternal health status during pregnancy and children´s medical history in early childhood.

METHODS

A retrospective study of cases (patients with MIH) and controls (patients without MIH) was designed between 2023 and 2024. A total of 280 children (cases = 140; controls = 140) aged 6 to 14 years (138 boys and 142 girls) were examined according to the European Academy of Pediatric Dentistry (EAPD) criteria for MIH. A survey was carried out with mothers regarding the potential exposure of their children to etiological factors of MIH. Possible prenatal and postnatal etiological factors were obtained through a personal interview with the patients' mothers. The statistical analysis was carried out with the contrast test and the chi-square test.

RESULTS

During pregnancy, folic acid consumption, alcohol intake, systemic viral and/or bacterial infections, and gestational diabetes were statistically significantly related to MIH, as were breastfeeding, asthma, and corticosteroid consumption during childhood.

CONCLUSIONS

Although there are different factors that may have statistically significant relationships with MIH, they cannot be predicted. Therefore, longitudinal studies, with a large sample size, are needed to determine the influence of prenatal and postnatal factors on the prevalence and severity of MIH in children.

Genetics Affecting the Prognosis of Dental Treatments

Genetics plays a significant role in determining an individual's susceptibility to dental diseases, the response to dental treatments, and the overall prognosis of dental interventions. Here, the authors explore the various genetic factors affecting the prognosis of dental treatments focusing on dental caries, orthodontic treatment, oral cancer, prosthodontic treatment, periodontal disease, developmental disorders, pharmacogenetics, and genetic predisposition to faster wound healing. Understanding the genetic underpinnings of dental health can help personalize treatment plans, predict outcomes, and improve the overall quality of dental care.

Influence of genetics on the occurrence of enamel hypomineralization affecting permanent and primary teeth: A scoping review

BACKGROUND

Molar incisor hypomineralization (MIH) is prevalent worldwide and is a challenge for clinicians who provide oral care to children. Molar incisor hypomineralization has been considered a multifactorial disturbance that results from a combination of environmental and genetic factors.

AIM

This scoping review followed the Joanna Briggs Institute protocol and aimed to identify the available evidence of the genetic influence on the etiology of MIH.

DESIGN

The search strategy was conducted in multiple databases, including PubMed, BVS, Embase, Web of Science, and Scopus. Two trained reviewers, requiring a third reviewer in case of disagreements, collected evidence.

RESULTS

Of 563 retrieved studies, 17 were included in the review. From 14 studies performed in humans, 10 investigated DNA polymorphisms, one analyzed DNA methylation, one aimed model of inheritance, and two focused on the phenotype in twins or in the family. Three animal studies were based on the null expression of genes.

CONCLUSION

This scoping review, based on the studies that used different methodologies, reinforces the hypothesis of a genetic contribution to the multifactorial etiology of MIH. The available data are limited in terms of size and origin of the samples. Hence, further genetic studies are still required.

Dentin hypersensitivity and toothache among patients diagnosed with Molar-Incisor Hypomineralization: A systematic review and meta-analysis

OBJECTIVES

To determine the prevalence of dentin hypersensitivity (DH) and toothache in patients with Molar-Incisor Hypomineralization (MIH); and evaluate whether patients with MIH have greater likelihood of presenting DH/toothache than controls.

DATA

Studies evaluating DH/toothache in patients with MIH were included. Studies focusing on other enamel defects were excluded.

SOURCES

Eight databases, including grey literature, were searched in January 2024.

STUDY SELECTION

The methodological quality of studies was assessed using the Joanna Briggs Institute checklist for Cross-sectional studies. Proportion and association meta-analyses, subgrouped by diagnostic methods, were conducted. The certainty of evidence was assessed using GRADE approach.

RESULTS

Fifteen studies were included in the qualitative analysis and fourteen in the meta-analyses. Two studies fulfilled all items of the methodological quality checklist. The overall prevalence of DH/toothache among patients with MIH was 45 %. Prevalence rates of 30 %, 47 %, and 55 % were estimated based on proxy reports, self-reports, and air stimulation, respectively. The overall prevalence of DH/toothache per tooth was 22 %, ranging from 16 % to 29 % according to the diagnostic method. Patients with MIH demonstrated higher likelihood of presenting proxy reports of DH/toothache compared to those without MIH (OR: 1.51, 95 % CI [1.23-1.85], P < 0.01, I2: 0 %). The certainty of evidence was very low, mainly due to the low methodological quality of included studies and high inconsistency.

CONCLUSIONS

The global prevalence of DH/toothache was 22 %, per tooth, and 45 % per patient. Estimates vary according to diagnostic methods. Patients with MIH showed higher likelihood of presenting proxy reports of DH/toothache than controls.

CLINICAL SIGNIFICANCE

This systematic review contributes valuable information to the dental literature by assessing the prevalence and associated factors of DH/toothache in patients with MIH. The findings can guide future research, inform clinical practices and public policy makers, and ultimately improve the management of oral health of patients with MIH.

REGISTRATION

PROSPERO CRD42023432805.

Association between molar hypomineralization, genes involved in enamel development, and medication in early childhood: A preliminary study

BACKGROUND

Molar hypomineralization (MH) is defined as a multifactorial condition, and thus, its presence may be defined by interactions between environmental and genetic factors.

AIM

To evaluate the association between MH, genes involved in enamel development, and the use of medication during pregnancy in early childhood.

DESIGN

One hundred and eighteen children, 54 with and 64 without MH, were studied. The data collected included demographics, socioeconomic data, and the medical history of mothers and children. Genomic DNA was collected from saliva. Genetic polymorphisms in ameloblastin (AMBN; rs4694075), enamelin (ENAM; rs3796704, rs7664896), and kallikrein (KLK4; rs2235091) were evaluated. These genes were analyzed by real-time polymerase chain reaction using TaqMan chemistry. The software PLINK was used to compare allele and genotype distributions of the groups and to assess the interaction between environmental variables and genotypes (p < .05).

RESULTS

The variant allele KLK4 rs2235091 was associated with MH in some children (odds ratio [OR]: 3.75; 95% confidence interval [CI] = 1.65-7.81; p = .001). Taking medications in the first 4 years of life was also associated with MH (OR: 2.94; 95% CI = 1.02-6.04; p = .041) and specifically in association with polymorphisms in ENAM, AMBN, and KLK4 (p < .05). The use of medications during pregnancy was not associated with MH (OR: 1.37; 95% CI = 0.593-3.18; p = .458).

CONCLUSION

The results of this study suggest that taking medication in the postnatal period appears to contribute to the etiology of MH in some evaluated children. There may be a possible genetic influence of polymorphisms in the KLK4 gene with this condition.

Potential Association of Molar-Incisor Hypomineralization (MIH) with Dental Agenesis and Infraoccluded Deciduous Molars: Is MIH Related to Dental Anomaly Pattern (DAP)? An Observational Cross-Sectional Study

Background: Dental Anomaly Pattern (DAP) is a collection of morphologic, numeric, and eruptive anomalies of teeth that are often observed together, suggesting a potential genetic relationship. Our objective was to assess the potential associations of Molar-Incisor Hypomineralization (MIH), a common developmental defect of enamel mineralization with a controversial etiology, with two specific components of DAP: (1) agenesis (AG) and (2) infraoccluded deciduous molars (IODM). Establishing such an association between MIH and one or both anomalies would provide evidence supporting a genetic link between MIH and DAP. Methods: We examined pretreatment intraoral standardized photographies and panoramic radiographs from 574 children aged 8-14 years, 287 having MIH and 287 without MIH, comparing the frequencies of AG and IODM in both groups. The subject samples were sourced from the databases of the orthodontic department at a university hospital. Results: The frequencies of AG in the MIH and non-MIH groups were 7% and 8%, respectively (p = 0.751). The corresponding frequencies of IODM were 27% and 19.2%, respectively (p = 0.082). That is, children with MIH did not exhibit an increased frequency of AG or IODM compared to those without MIH. Conclusions: These findings do not support the inclusion of MIH in DAP. Nevertheless, further analysis of possible associations is necessary to definitively validate or invalidate this hypothesis.

Prevalence and clinical presentation of molar incisor hypomineralisation among a population of children in the community of Madrid

OBJECTIVE

The main objective of this study was to estimate the prevalence of molar incisor hypomineralisation (MIH), an alteration of tooth enamel with an estimated worldwide prevalence rate of 14%, among children using primary care services in the Community of Madrid, Spain.

MATERIALS AND METHODS

This was a descriptive, cross-sectional and multicentre study. After calibrating all researchers and following the diagnostic criteria of the European Academy of Paediatric Dentistry (EAPD), children aged between 8 and 16 years who were users of the dental services at 8 primary oral health units of the Madrid Health Service (SERMAS) were included. The children underwent a dental examination, and the parents were asked to complete a questionnaire.

RESULTS

The prevalence of MIH was 28.63% (CI: 24.61-32.65%). The age cohorts most affected by MIH were 8 years (21.4%) and 11 years (20.7%). The presence of MIH was greater among girls (85; 60.71%) than among boys (55; 39.28%). The mean number of affected teeth per patient was 4.46 ± 2.8. The most frequently affected molar was the upper right first molar (74.3%), and the upper left central incisor was the most affected incisor (37.85%). Opacities were the defects most frequently recorded (63.57%).

CONCLUSIONS

The prevalence of MIH in this study is the highest of all relevant studies conducted in Spain.

Association of Three Genetic Loci with Molar Incisor Hypomineralization in Polish Children

BACKGROUND

Molar incisor hypomineralization (MIH) is a qualitative, demarcated enamel defect of hypomineralization affecting one to four first permanent molars, often with incisor involvement. Its etiology is complex. However, evidence suggests the influence of genetic factors, potentially including the single nucleotide polymorphisms (SNPs) rs2889956, rs4811117 and rs13058467, which were previously linked to MIH in a genome-wide association study of German children. The aim was to replicate analyses of possible associations between the SNPs and molar incisor hypomineralization in Polish children.

METHODS

The final study group consisted of 778 children aged 126-168 months old. Saliva samples were taken, and genomic DNA was extracted and genotyped using beadchip microarrays.

RESULTS

Among the 778 subjects, there were 68 (8.7%) subjects with MIH and 710 (91.3%) subjects without MIH. There were no significant differences in distributions in age, sex, or the frequency of caries in permanent dentition between the MIH and non-MIH groups. The rs2889956, rs4811117, and rs13058467 genotype distributions in the studied group conformed to the expected Hardy-Weinberg equilibria, and there were no significant differences in the distributions of their alleles or genotypes between the MIH and non-MIH groups.

CONCLUSION

Our replication study did not confirm highly significant associations between the single nucleotide polymorphisms rs2889956, rs4811117, and rs13058467 with molar incisor hypomineralization in Polish children.

Knowledge, experience, and perception of molar incisor hypomineralisation among dentists in the metropolitan area of Mexico City: a cross-sectional study

BACKGROUND

Molar-incisor hypomineralisation (MIH) is the most common developmental abnormality observed in teeth. Being a relatively new condition, its treatment can present a challenge for the dentist. There is currently no study available that has evaluated the knowledge of Mexican dental personnel. This study aimed to evaluate the knowledge, experience, and perceptions of dental surgeons regarding the detection, assessment, and treatment of MIH in the metropolitan area of Mexico City.

METHODS

A cross-sectional study was designed. Dentists from Mexico City and its metropolitan area were invited through social networks to answer a questionnaire of 30 questions related to MIH. Participants were classified into general practice dentists, paediatric dentists, and other speciality dentists. Pearson's chi-square test was used for data analysis.

RESULTS

The questionnaire was answered by 391 dentists. A total of 86% (338 out of 391) of them identified MIH lesions, while 84% of them reported having observed MIH lesions in their practice. The most frequently observed lesions were yellow-brown opacities which accounted for 47% of the lesions, 46% were white opacities, while only 7% were observed as post-eruptive fractures in the enamel as part of the manifestations of MIH. The most frequently reported problem in the management of teeth with MIH was insufficient training for treating children with MIH. A total of 84% of dentists stated that they would like more information on the treatment of MIH lesions.

CONCLUSIONS

Most of the surveyed dentists recognised MIH and reported having observed MIH lesions in their practice. Most of the dentists indicated that the main problem for the management of the MIH is the lack of training.

Asthma medication and risk of dental diseases in children - A prospective cohort study

BACKGROUND

Dental caries and enamel defects are the main causes of poor dental health in children, with a substantial impact on their well-being. Use of inhaled asthma medication is a suspected risk factor, but there is a lack of prospective studies investigating this and other prenatal and early life risk factors.

METHODS

Copenhagen Prospective Studies on Asthma in Childhood 2010 mother-child cohort (COPSAC2010 ) consists of 700 women who were recruited at 24 weeks of pregnancy. 588 of their children participated in a dental examination at 6 years of age (84%) at the COPSAC2010 research unit. Caries was defined as decayed, missing, or filled surfaces. Enamel defect was defined as demarcated opacity, post-eruptive enamel breakdown, and/or atypical restoration on at least one molar. Caries and enamel defects were assessed in both deciduous and permanent dentitions.

RESULTS

We found no associations between inhaled corticosteroids or β2 -agonists or asthma symptoms in early childhood and the risk of caries or enamel defects by 6 years of age. Furthermore, we found no strong pre-, peri-, or postnatal risk factors for dental diseases at 6 years, except from nominally significant associations between antibiotic use in pregnancy (OR = 1.25, [1.01-1.54]), maternal education level (OR = 1.57, [1.01-2.45]), having a dog at home (OR = 0.50, [0.27-0.93]), and risk of enamel defects.

CONCLUSIONS

Use of inhaled corticosteroids, β2 -agonists, or asthma symptoms in the first 6 years of life were not associated with the development of caries or enamel defects. This finding is reassuring for parents and physicians prescribing asthma medication for young children.

Real-World Evidence on the Prevalence of Molar Incisor Hypomineralization in School Children from Bucharest, Romania

Molar incisor hypomineralization (MIH) is an understudied and underrecognized clinical entity occurring in children. We performed a cross-sectional study to determine the real-world prevalence of MIH among school children undergoing routine dental checkups at one primary and middle school in Bucharest, Romania. Our study cohort consisted of 266 children with evaluable data, of which 143 (53.8%) were males, with a median age of 10 years old (interquartile range: 8-11 years). In this study cohort, we have identified a prevalence of 14.3% (n = 38 cases) of MIH. Among patients diagnosed with MIH, hypomineralizations were present in 47.4% of children on the maxillary first molar, 92.1% on the mandibular first molar, 94.7% on the maxillary incisor, 36.8% on the mandibular incisor, and 5.3% on the deciduous second molar. We identified the maxillary incisor and the mandibular first molar as the most important examined sites significantly associated with the presence of MIH (p < 0.0001 each), highlighting the importance of paying focused attention to these sites during routine dental care in children. In order to establish the diagnosis of MIH, findings of hypomineralization should be present on at least one permanent first molar, according to the case definition currently in use; this definition does not include findings on the incisors. Thus, our finding that hypomineralization of the maxillary incisors is significantly associated with MIH is particularly important. While incisor hypomineralization is not diagnostic of MIH, based on our results, we conclude that it should raise the suspicion of MIH and lead to an attentive examination of the permanent molars in order to establish timely diagnosis.

Insights into molar-incisor hypomineralisation in past populations: A call to anthropologists

OBJECTIVE

Molar incisor hypomineralisation (MIH) is a developmental defect of enamel affecting the first permanent molars and often the incisors and affecting approximately 13% of the current population worldwide. Here, we aim to highlight potential differential diagnoses of MIH in archaeological collections (taphonomic discoloration, amelogenesis imperfecta, fluorosis, rachitic teeth, etc.).

METHODS

Causative factors of dental discolourations are identified through a literature review.

RESULTS

In an archaeological context, the sediments contained in the burial soil can lead to tooth discoloration. Taphonomic staining of the dentition may have a similar appearance to enamel hypomineralisation, and thus is a confounding factor that has the potential to cause miscalculation of the true prevalence of MIH within archaeological collections. Some rare medieval cases are reported in the modern literature but without microanalysis, misdiagnosis is possible. The aetiological factors of MIH are unknown but probably follow the multifactorial model involving systemic medical and genetic factors.

CONCLUSIONS

Systematic detection and diagnosis of MIH during anthropological studies is therefore of great interest.

SIGNIFICANCE

The hypotheses that only contemporary agents are causative factors of MIH could be refuted by the discovery of individuals living before medication or pollutants. The identification of MIH in a group of individuals also provides information regarding the health status of a population and reflects stress occurring during the period of mineralisation of the first permanent molars after secretion of the enamel matrix.

LIMITATIONS

Taphonomic alterations of archaeological remains prevent MIH diagnosis.

SUGGESTIONS FOR FUTURE RESEARCH

MIH diagnosis can be difficult in archaeological series and further non-destructive methods (microtomography, elemental analyses, etc.) are required.

MIH and Dental Caries in Children: A Systematic Review and Meta-Analysis

(1) Background: Molar-incisor hypomineralization (MIH) is a clinical condition affecting permanent teeth in children, with a documented rising trend in the last two decades. The aim of the present study was to analyze and synthesize the available evidence on caries experience (dmft/DMFT) and MIH in children. (2) Methods: A systematic review and meta-analysis were conducted according to the PRISMA statement. (3) Results: 59 papers published between 2007 and 2022 were included in the qualitative synthesis and 18 in the meta-analysis. The total sample of subjects was 17,717 (mean: 896), of which 2378 (13.4%) had MIH (mean: 119), with a girl/boy ratio of 1:1. The mean age of the enrolled participants was 8.6 (age range 7-10 years). Meta-analysis showed that MIH has a positive correlation with both dmft (effect size of 0.67, 95% CI [0.15, 1.19]) and DMFT (effect size of 0.56, 95% CI [0.41, 0.72]); (4) Conclusions: Children with MIH should be diagnosed correctly and on time. Treatment and management options for moderate and severe forms of MIH should consider prognosis based on known risk factors, and secondary and tertiary prevention policies should also consider the multifactorial nature of caries etiology.

Association between genetic factors and molar-incisor hypomineralisation or hypomineralised second primary molar: A systematic review

OBJECTIVE

To determine the association between genetic factors and molar-incisor hypomineralisation (MIH) and/or hypomineralised second primary molars by means of a systematic review.

DESIGN

A search was performed in Medline-PubMed, Scopus, Embase and Web of Science databases; manual search and search in gray literature were also performed. Selection of articles was performed independently by two researchers. A third examiner was involved in cases of disagreement. Data extraction was performed using an Excel® spreadsheet and independent analysis was performed for each outcome.

RESULTS

Sixteen studies were included. There was an association between MIH and genetic variants related to amelogenesis, immune response, xenobiotic detoxification and other genes. Moreover, interactions between amelogenesis and immune response genes, and SNPs in the aquaporin gene and vitamin D receptors were associated with MIH. Greater agreement of MIH was found in pairs of monozygotic twins than dizygotic twins. The heritability of MIH was 20 %. Hypomineralised second primary molars was associated with SNPs in the hypoxia-related HIF-1 gene and methylation in genes related to amelogenesis.

CONCLUSION

With very low or low certainty of evidence, an association was observed between MIH and SNPs in genes associated with amelogenesis, immune response, xenobiotic detox and ion transport. Interactions between genes related to amelogenesis and immune response as well as aquaporin genes were associated to MIH. With very low certainty of evidence, hypomineralised second primary molars was associated to a hypoxia-related gene and to methylation in genes related to amelogenesis. Moreover, higher agreement of MIH in pairs of monozygotic twins than dizygotic twins was observed.

Relationship between the TGFBR1 Gene and Molar Incisor Hypomineralization

BACKGROUND

Molar Incisor Hypomineralization Syndrome (MIH) is a problem of increasing incidence that represents a new challenge in the dental treatment of many of the children we see in our dental offices. Understanding the etiology of this syndrome (still unknown) will help us to prevent the appearance of this process. Lately a certain genetic relationship has been suggested in the syndrome. The aim of the present study was to explore the relationship between activation of the TGFBR1 gene and the development of MIH, as recent studies suggest that there may be an association in this regard.

MATERIALS AND METHODS

The study sample consisted of 50 children between 6-17 years of age with MIH, each with at least one parent and a sibling with or without MIH, and a group control of 100 children without MIH. The condition of the permanent molars and incisors was evaluated and recorded based on the criteria of Mathu-Muju and Wright. Saliva samples were collected after washing and rinsing of the oral cavity. Genotyping was performed with the saliva samples for the selection of a target polymorphism of the studied gene (TGFBR1).

RESULTS

The mean age was 9.7 years (SD 2.36). Of the 50 children with MIH, 56% were boys and 44% girls. The degree of MIH was predominantly severe (58%), with moderate and mild involvement in 22% and 20% of the cases, respectively, according to the classification of Mathu-Muju. The allelic frequencies were seen to behave as expected. The logistic regression analysis aimed to relate each polymorphism to the presence or absence of the factors. These results were inconclusive, with no evidence suggesting an alteration of the TGFBR1 gene to be related to the appearance of MIH.

CONCLUSIONS

Within the limitations posed by a study of these characteristics, it can be affirmed that no relationship has been found between the TGFBR1 gene and the appearance of molar incisor hypomineralization.

Etiological Factors of Molar Incisor Hypomineralization: A Systematic Review and Meta-Analysis

Molar incisor hypomineralization (MIH) is a defect of the dental enamel that predominantly affects first molars and permanent incisors. Identifying the significant risk factors associated with MIH occurrence is essential for the implementation of prevention strategies. The purpose of this systematic review was to determine the etiological factors associated with MIH. A literature search was carried out from six databases until 2022; it covered pre-, peri-, and postnatal etiological factors. The PECOS strategy, PRISMA criteria, and the Newcastle-Ottawa scale were used, and 40 publications were selected for qualitative analysis as well as 25 for meta-analysis. Our results revealed an association between a history of illness during pregnancy (OR 4.03 (95% CI, 1.33-12.16), p = 0.01) and low weight at birth (OR 1.23 (95% CI, 1.10-1.38), p = 0.0005). Furthermore, general illness in childhood (OR 4.06 (95% CI, 2.03-8.11), p = 0.0001), antibiotic use (OR 1.76 (95% CI, 1.31-2.37), p = 0.0002), and high fever during early childhood (OR 1.48 (95% CI, 1.18-1.84), p = 0.0005) were associated with MIH. In conclusion, the etiology of MIH was found to be multifactorial. Children with health disorders in the first years of life and those whose mothers underwent illnesses during pregnancy might be more susceptible to MIH.

Enamel Phenotypes: Genetic and Environmental Determinants

Dental enamel is a specialized tissue that has adapted over millions of years of evolution to enhance the survival of a variety of species. In humans, enamel evolved to form the exterior protective layer for the crown of the exposed tooth crown. Its unique composition, structure, physical properties and attachment to the underlying dentin tissue allow it to be a resilient, although not self-repairing, tissue. The process of enamel formation, known as amelogenesis, involves epithelial-derived cells called ameloblasts that secrete a unique extracellular matrix that influences the structure of the mineralizing enamel crystallites. There are over 115 known genetic conditions affecting amelogenesis that are associated with enamel phenotypes characterized by either a reduction of enamel amount and or mineralization. Amelogenesis involves many processes that are sensitive to perturbation and can be altered by numerous environmental stressors. Genetics, epigenetics, and environment factors can influence enamel formation and play a role in resistance/risk for developmental defects and the complex disease, dental caries. Understanding why and how enamel is affected and the enamel phenotypes seen clinically support diagnostics, prognosis prediction, and the selection of treatment approaches that are appropriate for the specific tissue defects (e.g., deficient amount, decreased mineral, reduced insulation and hypersensitivity). The current level of knowledge regarding the heritable enamel defects is sufficient to develop a new classification system and consensus nosology that effectively communicate the mode of inheritance, molecular defect/pathway, and the functional aberration and resulting enamel phenotype.

Prevalence and risk factors of molar incisor hypomineralization in the Middle East: A systematic review and meta-analysis

Objectives

Molar incisor hypomineralization (MIH) is a growing global concern. Herein, we conducted a systematic review and meta-analysis of the prevalence and associated factors/risk factors of MIH in the Middle East (ME).

Methods

This systematic review and meta-analysis included studies on children with at least one first permanent molar affected by MIH, aged 5-18 years, without syndromes or congenital anomalies, and residing in the ME and included cross-sectional, case-control, and cohort studies. Keywords related to MIH and ME countries were systematically searched until January 10, 2021 in four databases, PubMed, Google Scholar, Science Direct, and the Cochrane Library, following the specified eligibility criteria. The Joanna Briggs Institute quality assessment tool was used to evaluate all included studies. Meta-analyses were conducted to assess the effect of risk factors. The study protocol was registered on the PROSPERO International Prospective Register of Systematic Reviews (Registration No. 247391).

Results

After screening 4,373 documents, 29 eligible studies with a total of 32,636 children aged 7-12 years were included from 11 countries. The frequency of MIH reported in the ME ranged from 2.3% to 40.7%, with a mean prevalence of 15.05%. Pregnancy and early childhood illnesses (odds ratio [OR]: 2.26, 95% confidence interval [CI]: 1.91-2.68; P < 0.001) and factors related to delivery (OR: 2.4, 95% CI: 1.55-3.72; P < 0.001) were statically significantly associated with MIH.

Conclusion

The mean prevalence of MIH in ME aligns with the global MIH prevalence rate. Illnesses and delivery complications are risk factors that could be controlled to prevent MIH. As included studies showed high heterogeneity in the meta-analyses, further evidence from the ME is needed to assess the prevalence and other associated environmental risk factors for MIH.

Association between respiratory diseases and molar-incisor hypomineralization: A systematic review and meta-analysis

The molar-incisor permineralização (MIH) is a qualitative enamel developing abnormality involving the occlusal and/or incisal third of one or more molars or permanent incisors, caused by systemic factors. Several systemic disorders and environmental factors, such as respiratory diseases, have been reported as probable causes of MIH. Thus, this work aimed to evaluate whether respiratory diseases and MIH are associated. The searches were carried out in electronic databases, including PubMed, Scopus, Web of Science, the Cochrane Library, LILACS, OpenGrey, and Google Scholar. The acronym PECO was used, in which the P (population) was humans in permanent dentition stage; (E-exposure) molar-incisor hypomineralization; (C-comparison) reference population and (O - outcome) respiratory diseases. After the search retrieval, the duplicates were removed, and the articles were evaluated by title and abstract; then, the papers were read and thoroughly assessed. After selection, the risk of bias assessment was performed using the Newcastle-Ottawa Scale (NOS) for observational studies. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool was used to assess the level of evidence. Three thousand six hundred and sixty six were found through the searches. After exclusion by duplicates, title, abstract, and full-reading, 13 articles remained. The articles included in this review evaluated the association of MIH with asthma, tonsilitis, pneumonia, and bronchitis. Most reports showed a low risk of bias. When exploring through GRADE, a very low level of evidence was found. We observed that the included studies showed that children with MIH had more respiratory diseases than the group that did not have MIH.

Systematic review registration

https://osf.io/un76d.

Knowledge, perceptions, attitudes, and clinical experiences on molar incisor hypomineralization among Syrian pediatric dentists and general dental practitioners: a cross-sectional study

BACKGROUND

Molar incisor hypomineralization (MIH) is a widespread oral health problem. Dentists encounter several challenges regarding MIH management worldwide. The aim of this study was to evaluate and compare the knowledge, perceptions, attitudes, and clinical experiences on MIH among general dental practitioners and pediatric dentists in Syria.

METHODS

All general dental practitioners and pediatric dentists belonging to the Syrian Dental Syndicate of Damascus were invited to complete a cross-sectional structured questionnaire (n = 1936). The questionnaire consisted of four sections and required responses regarding demographic data, knowledge, perceptions, attitudes, and experiences on MIH. Data were analyzed with Pearson's chi-square test and multivariate regression models using SPSS Ver. 23.0.

RESULTS

The overall response rate was 36.31% (703/1936). Pediatric dentists were significantly more familiar with MIH (p < 0.001) and more confident when diagnosing it (p < 0.001). Most participants (43.95%) perceived an increase in MIH prevalence in Syria. Stainless steel crowns were the most favorable restorative material for molars with post-eruptive breakdown (51.38%). As for molars and incisors with opacities, composite resin was preferred with (41.82%), and (67.51%) respectively. General dental practitioners requested further training regarding MIH treatment (p < 0.001).

CONCLUSIONS

Pediatric dentists were equipped with further knowledge regarding MIH, and were more confident when diagnosing it. There is a need for additional training and education for general dental practitioners. Most respondents perceived an increase in the prevalence of MIH. There is a dearth of data regarding MIH prevalence in Syria. The materials of choice for restoring teeth with MIH were stainless steel crowns and composite resin.

Identification by whole-exome sequencing of new single-nucleotide polymorphisms associated with molar-incisor hypomineralisation among the Lebanese population

OBJECTIVE

Molar-incisor hypomineralization (MIH) is a developmental qualitative enamel defect, causing a worldwide challenging dental problem. The etiology of this defect remains unclear. Here we identify by whole-exome sequencing (WES) new single-nucleotide polymorphisms (SNPs) in genes expressed during enamel mineralization and in those modulating prenatal, natal and postnatal risk factors among the Lebanese MIH children: immune system and xenobiotic detoxification.

DESIGN

Dental examination for MIH was performed based on the MIH index for diagnostic criteria. Saliva samples were collected from 37 non-related, MIH-diagnosed subjects for DNA extraction. WES was performed on the Illumina HiSeq2000 platform. The χ² test and Fisher's exact test were used to determine relationship between SNPs frequencies and MIH. OR and its 95% CI were used to report the strength of association. The significance threshold was set at 0.05.

RESULTS

Among the Lebanese population, 37 SNPs presented a significant association with MIH in the following genes: AMTN, MMP-20, STIM1, STIM2, ORAI1, SLC34A2, SLC34A3, VDR, PVALB, HSP90B1, TRPM7, SLC24A4, CA6, SLC4A2, TNFRSF11A, IL10RB, ARNT, ESR1 and CYP1B1.

CONCLUSION

This is the first WES study conducted in patients with MIH. Yet, interactions between polymorphisms in different gene categories are to be investigated for a better assessment of MIH susceptibility.

"Knowledge, clinical experience, and perceived need for training regarding molar-incisor hypomineralization among a group of Egyptian dental students: a cross-sectional study"

BACKGROUND

Molar-Incisor Hypomineralization (MIH) is a common oral health condition that can lead to difficulties and complications for both dental professionals and patients. It also has a negative impact on the oral health-related quality of life. The present study aimed to assess the knowledge, clinical experience, and perceived need for training of a group of Egyptian dental students regarding MIH.

METHODS

Paper-based survey administration method was used to collect the responses of dental students regarding their knowledge, clinical experience, and perceived need for training about MIH. The survey consisted of two sections of questions regarding clinical features, etiological factors, prevalence, materials used in treating these teeth, factors affecting the choice of restorative materials, and their preferences regarding clinical training of MIH. Descriptive statistics was used for the data analysis by using SPSS® Statistics Version 26.

RESULTS

About two-thirds of the respondents were familiar with MIH (69.2%). The vast majority of students (87.8%) had difficulty distinguishing MIH as a developmental defect that differs from other tooth conditions (p < 0.001); most commonly enamel hypoplasia. The most common defects seen by the respondents were yellow/brown opacities (59.1%). Nearly half of the students (45.2%) choose composite resin as the material of choice for the treatment of MIH-affected teeth with aesthetics being the most common factor affecting the selection of restorative material. Almost all students expressed their needs for further clinical training on MIH, especially on treatment aspects.

CONCLUSIONS

Most students are familiar with MIH theoretically. However, there is an urgent need to include clinical training on MIH diagnosis in the practical sessions of pediatric dentistry courses.

Prevalence and Possible Etiological Factors of Molar-Incisor Hypomineralization (MIH) in Population of Silesian Children in Poland: A Pilot Retrospective Cohort Study

(1) Background: This pilot retrospective cohort research study regarded the frequency of the prevalence of molar-incisor hypomineralization (MIH) in a population of Silesian children in Poland. The evaluation of the potential environmental etiological factors was performed and the correlation between the environmental factors and MIH was analyzed. (2) Methods: A total of 613 children were randomly enrolled in the pilot study (9.0 years ± 1.9). A survey was carried out with mothers regarding the potential exposure to environmental etiological factors of MIH in their children. The patients’ clinical assessments were carried out in the dental unit. (3) Results: The frequency of prevalence of MIH in the population of Silesian children was established at the level of 6.2% (p < 0.05). MIH symptoms were significantly associated with otitis in early childhood (OR = 2.50), atopic dermatitis (OR = 5.69), and premature delivery before 38 weeks of pregnancy (OR = 2.88). (4) Conclusions: MIH was observed in 6.2% of the population of Silesian children, and there was a relationship between environmental risk factors such as otitis, atopic dermatitis, premature birth, and MIH expression. Therefore, further research is needed to determine the influence of pre-, peri-, postnatal, and prophylactic factors on the frequency and severity of MIH symptoms in children.

Is Aberrant DNA Methylation a Key Factor in Molar Incisor Hypomineralization?

Molar incisor hypomineralization (MIH) is a qualitative disturbance of the enamel of the permanent molars and/or incisors. Its etiology is not clearly defined but is connected with different factors occurring before and after birth. It remains difficult to identify a single factor or group of factors, and the problem is further complicated by various overlapping mechanisms. In this study, we attempted to determine whether DNA methylation-an epigenetic mechanism-plays a key role in the etiology of MIH. We collected the epithelium of the oral mucosa from children with MIH and healthy individuals and analyzed its global DNA methylation level in each child using a 5-mC DNA ELISA kit after DNA isolation. There was no statistically significant difference between the global DNA methylation levels in the study and control groups. Then, we also analyzed the associations of the DNA methylation levels with different prenatal, perinatal, and postnatal factors, using appropriate statistical methods. Factors such as number of pregnancies, number of births, type of delivery, varicella infection (under 3 years old), and high fever (under 3 years old) were significantly important. This work can be seen as the first step towards further studies of the epigenetic background of the MIH etiology.

Prevalence of molar incisor hypomineralization among school children in Rome, Italy

Molar incisor hypomineralization (MIH) is a highly prevalent condition associated with increased caries experience, dental pain and treatment need. Aim of this study was to determine the prevalence and severity of MIH in a group of 7–8 years old primary school children living in Rome, Italy; and to assess the association with caries experience and possible perinatal risk factors. A survey has been conducted in the city of Rome, between April 2019 and March 2020 with a total of 49 primary schools and 176 2nd grade primary school classes and a total of 3611 children being involved. Of these, a subset of 346 children of 21 primary schools was selected for the epidemiological investigation. The prevalence of MIH was of 18.2%, with girls showing twice the probability of being subject to a mild-severe condition. Molar location was present in 71.4%, while location on both molar plus incisor was present in 28.6% of cases. The mean DMFT was 0.44 ± 0.78, “D” was 0.17 ± 0.58; the mean dmft was 1.7 ± 2.56, “d” was 1.32 ± 2.21. Female gender, caries experience, insufficient oral hygiene were risk factors. The incidence of MIH is increasing in the pediatric population. Knowledge about diagnosis and treatment options should be disseminated among dental professionals.

An update of the aetiological factors involved in molar incisor hypomineralisation (MIH): a systematic review and meta-analysis

PURPOSE

To systematically review the aetiological factors associated with molar incisor hypomineralisation (MIH). To this day, the aetiology remains unknown. Determining risk factors would allow risk assessment and enhance early diagnosis of MIH in young patients. The aim was to assess, evaluate and summarise the relationship between MIH and reported aetiological hypotheses.

METHODS

Electronic database searches of MEDLINE, EMBASE, EBSCO, LILACS and Cochrane Library were conducted. Authors conformed to PRISMA guidelines. Studies were screened, data extracted, assessment of risk of bias and calibration was completed by two independent reviewers. Meta-analyses with heterogeneity calculations were performed.

RESULTS

Of the potential 8949 studies, 64 studies were included in the qualitative analysis whilst 45 were included in the quantitative analysis. Prenatal factors: results are inconclusive as only unspecified maternal illnesses appear to be linked to MIH. Perinatal factors: prematurity (OR 1.45; 95% CI 1.24-1.70; p = 0.0002) and caesarean delivery (OR 1.45; 95% CI 1.09, 1.93; p < 0.00001) are associated with an increased risk of developing MIH. Birth complications are also highlighted. These three factors can lead to hypoxia, and children with perinatal hypoxia are more likely to develop MIH (OR 2.76; 95% CI 2.09-3.64; p < 0.0001). Postnatal factors: measles, urinary tract infection, otitis media, gastric disorders, bronchitis, kidney diseases, pneumonia and asthma are associated with MIH. Fever and antibiotic use, which may be considered as consequences of childhood illnesses, are also associated with MIH. Genetic factors: an increasing number of studies highlight the genetic and epigenetic influences in the development of MIH.

CONCLUSION

Several systemic and genetic and/or epigenetic factors acting synergistically or additively are associated with MIH, revealing a multifactorial aetiology model. Peri- and postnatal aetiological factors are more likely to increase the odds of causing MIH than prenatal factors.

An update of treatment modalities in children and adolescents with teeth affected by molar incisor hypomineralisation (MIH): a systematic review

PURPOSE

To systematically review the treatment modalities for molar-incisor hypomineralisation for children under the age of 18 years. The research question was, 'What are the treatment options for teeth in children affected by molar incisor hypomineralisation?'

METHODS

An electronic search of the following electronic databases was completed MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, LILACS, Google Scholar and Open Grey identifying studies from 1980 to 2020. The PRISMA guidelines were followed. The studies were screened, data extracted and calibration was completed by two independent reviewers.

RESULTS

Of 6220 potential articles, 34 studies were included. Twenty studies investigated management of molars with fissure sealants, glass ionomer cement, polyacid modified resin composite, composite resin, amalgam, preformed metal crowns, laboratory-manufactured crowns and extractions. In four articles management of incisors with microabrasion, resin-infiltration and a combination of approaches was reported. Eight studies looked at strategies to mineralise MIH-affected teeth and/or reduce hypersensitivity. Two studies investigated patient-centred outcomes following treatment. Due to the heterogeneity between the studies, meta-analysis was not performed.

CONCLUSION

The use of resin-based fissure sealants, preformed metal crowns, direct composite resin restorations and laboratory-made restorations can be recommended for MIH-affected molars. There is insufficient evidence to support specific approaches for the management of affected incisors. Products containing CPP-ACP may be beneficial for MIH-affected teeth.

Prevalence and possible aetiological factors of molar incisor hypomineralisation in Saudi children: A cross-sectional study

Background

A new charting system for molar incisor hypomineralisation (MIH) was recently published and is based on the European Academy of Paediatric Dentistry (EAPD) criteria. This charting system aims to standardise MIH data collection. Therefore, there is a need for new MIH prevalence studies using the currently recommended charting-form.

Aim

To investigate the prevalence and possible aetiological factors of MIH in randomly selected Saudi schoolchildren aged 8–12 years in Riyadh.

Design

A randomly selected sample of Saudi schoolchildren aged 8–12 years attending elementary schools in Riyadh was examined using the EAPD short-form charting, which was recently recommended for the standardised collection of epidemiological data on MIH. To investigate possible aetiological factors of MIH, we collected demographic, pregnancy, and medical history using a questionnaire.

Results

A total of 1,562 children participated in the study (48.8% girls, 51.2% boys). The prevalence of MIH was 15.2%, without a significant difference in the prevalence between the sexes. Among those with MIH, 79.4% had affected incisors and 55.9% had hypomineralised second primary molars. The most prevalent clinical defect was demarcated opacities, and the maxillary arch was more affected. Permanent incisors were more affected in boys than in girls. Defects of the first permanent molars were more severe in terms of clinical status and lesion extent than defects of the permanent incisors. MIH was significantly more prevalent in children with a history of early childhood ear infections, respiratory distress, and tonsillitis.

Conclusions

MIH is common in Saudi schoolchildren living in Riyadh, with no gender predilection. Hypomineralised second primary molars can be used to predict MIH. MIH was significantly associated with childhood illness during the first three years of life, including ear infection, respiratory distress, and tonsillitis.

Best clinical practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralisation (MIH): an updated European Academy of Paediatric Dentistry policy document

AIM

To update the existing European Academy of Paediatric Dentistry (EAPD) 2010 policy document on the 'Best Clinical Practice guidance for clinicians dealing with children presenting with Molar-Incisor-Hypomineralisation (MIH).'

METHODS

Experts, assigned the EAPD, worked on two different topics: (A) Aetiological factors involved in MIH, and (B) Treatment options for the clinical management of MIH. The group prepared two detailed systematic reviews of the existing literature relevant to the topics and following a consensus process produced the updated EAPD policy document on the 'Best Clinical Practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralisation (MIH).' The GRADE system was used to assess the quality of evidence regarding aetiology and treatment which was judged as HIGH, MODERATE, LOW or VERY LOW, while the GRADE criteria were used to indicate the strength of recommendation regarding treatment options as STRONG or WEAK/CONDITIONAL.

RESULTS

(A) Regarding aetiology, it is confirmed that MIH has a multifactorial aetiology with the duration, strength and timing of occurrence of the aetiological factors being responsible for the variable clinical characteristics of the defect. Perinatal hypoxia, prematurity and other hypoxia related perinatal problems, including caesarean section, appear to increase the risk of having MIH, while certain infant and childhood illnesses are also linked with MIH. In addition, genetic predisposition and the role of epigenetic influences are becoming clearer following twin studies and genome and single-nucleotide polymorphisms analyses in patients and families. Missing genetic information might be the final key to truly understand MIH aetiology. (B) Regarding treatment options, composite restorations, preformed metal crowns and laboratory indirect restorations provide high success rates for the posterior teeth in appropriate cases, while scheduled extractions provide an established alternative option in severe cases. There is great need for further clinical and laboratory studies evaluating new materials and non-invasive/micro-invasive techniques for anterior teeth, especially when aesthetic and oral health related quality of life (OHRQoL) issues are concerned.

CONCLUSIONS

MIH has been studied more extensively in the last decade. Its aetiology follows the multifactorial model, involving systemic medical and genetic factors. Further focused laboratory research and prospective clinical studies are needed to elucidate any additional factors and refine the model. Successful preventive and treatment options have been studied and established. The appropriate choice depends on the severity of the defects and the age of the patient. EAPD encourages the use of all available treatment options, whilst in severe cases, scheduled extractions should be considered.

Molar Incisor Hypomineralisation: Current Knowledge and Practice

BACKGROUND

Molar incisor hypomineralisation (MIH) is a common developmental dental condition that presents in childhood. Areas of poorly formed enamel affect one or more first permanent molars and can cause opacities on the anterior teeth. MIH presents a variety of challenges for the dental team as well as functional and social impacts for affected children.

OBJECTIVES

Here, we provide an up-to-date review of the epidemiology, aetiology, diagnosis and clinical management of MIH.

MATERIALS AND METHODS

A review of the contemporary basic science and clinical literature, relating to MIH, was undertaken using information obtained (up to 10 April 2020) from the electronic databases PubMed, Scopus, Web of Science and the Cochrane Library.

RESULTS

There is a growing body of evidence relating to the aetiology, presentation and clinical management of MIH. Current knowledge appears to be focused on potential genetic aspects, as well as the development and validation of indices for the diagnosis and management of MIH. There has also been increasing recognition of the global and individual burden of this common condition.

CONCLUSIONS

Dental health professionals should regularly appraise the basic science and clinical MIH literature to ensure that they provide the best possible short- and long-term care for their young patients.

Frequency of molar incisor hypomineralization and associated factors among children with special health care needs

BACKGROUND

Molar incisor hypomineralization (MIH) is a frequently encountered oral condition that varies from mild opacities to posteruptive enamel breakdown. No previous published studies have investigated the frequency of MIH and associated risk factors among children with special health care needs (CSHCN) to our awareness.

OBJECTIVES

Assess the frequency of MIH and associated risk factors among CSHCN.

DESIGN

Cross-sectional.

SETTING

Schools in provincial city of Saudi Arabia.

PATIENTS AND METHODS

The study was conducted among 400 (180 boys and 220 girls) special needs children. Diagnosis of MIH was according to the European Academy of Paediatric Dentistry criteria.

MAIN OUTCOME MEASURE

Result of logistic regression analysis that assessed the association between MIH prevalence and associated prenatal, perinatal, and postnatal factors.

SAMPLE SIZE

400 (180 boys and 220 girls) special needs children.

RESULTS

Among 400 CSHCN, 98 (24.5%) presented with MIH. Children with multiple disabilities had a 3.89 times greater risk of MIH (95% CI: 1.91-6.19, P=.002). Children with positive prenatal factors had an adjusted odds ratio (aOR) of 2.31 times for MIH (95% CI: 1.22-4.73, P=.012). Children with a childhood infection history had an aOR of 2.43 times for MIH (95% CI: 1.31-5.85, P=.014). Children with a breastfeeding history >18 months had an aOR of 3.73 for MIH (95% CI: 1.62-8.60, P=.002). Permanent maxillary first molars were the most frequently affected teeth, and demarcated opacity was the most frequent MIH type.

CONCLUSION

MIH should be recognized as one of the prevalent oral health problems among CSHCN to prevent tooth mortality.

LIMITATIONS

A cross-sectional study cannot establish a causal relationship.

CONFLICTS OF INTEREST

None.

Molar incisor hypomineralization: A review and prevalence in Japan

Molar incisor hypomineralization (MIH) is defined as hypomineralization of systemic origin of one to four first permanent molars, and incisors are also frequently affected. This disorder is a serious concern in pediatric dentistry. Teeth affected by MIH have many dental problems, such as hypersensitivity, poor aesthetics, and rapid progression of dental caries. The prevalence of MIH ranges from 2.8% to 21% among studies with more than 1000 subjects in different countries and age groups. The etiology of MIH is unclear, but genetic and environmental factors have been proposed. This review describes the prevalence, etiology, and clinical management of MIH. A detailed description of MIH prevalence in Japan is also provided.

Assessment of Genetical, Pre, Peri and Post Natal Risk Factors of Deciduous Molar Hypomineralization (DMH), Hypomineralized Second Primary Molar (HSPM) and Molar Incisor Hypomineralization (MIH): A Narrative Review

OBJECTIVES

Analyze defects in the state of maturation of the enamel result in an adequate volume of enamel, but in an insufficient mineralization, which can affect both deciduous teeth and permanent teeth. Among the most common defects, we recognize Deciduous Molar Hypominerlization (DMH), Hypomineralized Second Primary Molar (HSPM), and Molar Incisor Hypomineralization (MIH). These, in fact, affect the first deciduous molars, the second deciduous molars and molars, and permanent incisors, respectively, but their etiology remains unclear. The objective of the paper is to review studies that focus on investigating possible associations between genetic factors or prenatal, perinatal, and postnatal causes and these enamel defects.

MATERIALS AND METHODS

A comprehensive and bibliometric search for publications until January 2021 was conducted. The research question was formulated following the Population, Intervention, Comparison, Outcome strategy. Case-control, cross-sectional, cohort studies, and clinical trials investigating genetic and environmental etiological factors of enamel defects were included.

RESULTS

Twenty-five articles are included. For genetic factors, there is a statistical relevance for SNPs expressed in the secretion or maturation stage of amelogenesis (16% of studies and 80% of studies that investigated these factors). For prenatal, perinatal, and postnatal causes, there is a statistical relevance for postnatal factors, such as the breastfeeding period (2%), asthma (16%), high fever episodes (20%), infections/illnesses (20%), chickenpox (12%), antibiotic intake (8%), diarrhea (4%), and pneumonia (4%).

CONCLUSIONS

The results are in agreement with the multifactorial idea of the dental enamel defects etiology, but to prove this, further studies enrolling larger, well-diagnosed, and different ethnic populations are necessary to expand the investigation of the genetic and environmental factors that might influence the occurrence of DMH, HPSM, and MIH.

Molar and Incisor Hypomineralization

Molar and incisor hypomineralization is a developmental defect that is systemic in origin that affects one or more than one permanent first molars, and is often associated with permanent incisors. It is usually characterized by well demarcated opacities and qualitative enamel defects caused by decreased inorganic enamel components, and reduced mineralization. It can cause esthetic, functional, psychological, and behavioral problems in children. Its reported prevalence varies widely, from 2.5% to 40.2%. Multiple aspects of dental treatment for it are challenging, such as behavior management, difficulty in achieving adequate local anesthesia, tooth hypersensitivity, and retention of restorations. This review discusses the most important considerations pertaining to its prevalence, severity, etiology, differential diagnosis, and some of the challenges and treatment modalities applicable in young patients. Data is collected from PubMed, Medline, and Embase databases.

Enamel opacities in all other than Molar Incisor Hypomineralisation index teeth of adolescents

BACKGROUND

There are scarce data on the hypomineralisation of other permanent teeth (HOPT) than the index teeth of Molar Incisor Hypomineralisation (MIH).

AIM

To report on the prevalence and surface pattern of HOPT and seek associations with MIH.

DESIGN

Representative samples of urban Greek 14-year-olds were examined in classroom with a dental mirror. Their enamel defects were recorded using EAPD criteria for MIH. Descriptive statistics and correlation tests for HOPT vs previously reported MIH findings in the same samples were applied.

RESULTS

HOPT prevalence in 1156 consented adolescents was 22.9%. 148 (16.2%) of 912 no-MIH children had HOPT; 117 (48.1%) of the 244 MIH children had HOPT too (OR 3.0, 95% CI 2.4-3.6). There were more HOPT teeth per child in the MIH vs no-MIH children (P < .001). HOPT tooth frequency was as follows: second molar 33.7%, canine 25.7%, first premolar 23.6%, and second premolar 17.0%. Enamel breakdown was seen in 5.3% HOPT children. Vestibular to intraoral surface defect ratio differed between jaws (maxilla 187/88, mandible 149/17, P < .05).

CONCLUSIONS

Hypomineralisation defects in the MIH non-index teeth collectively had comparable prevalence and tooth surface patterns to MIH, but much lower severity. MIH was predictor for HOPT.

Molar Incisor Hypomineralization in Children with Intellectual Disabilities

The aim of the study is to compare the frequency and the distribution of molar incisor hypomineralization (MIH) in children with intellectual disabilities.

METHODS

Seventy-two children with intellectual disabilities and 72 healthy children were included in the study. They ranged in age from 5 to 18 years with the same distribution by age and sex. Standard clinical examination was performed, at a dental clinic or in the institution where the children lived, by using a dental mirror and a probe, according the European Academy of Paediatric Dentistry judgment criteria for MIH.

RESULTS

Among the 72 children with intellectual disabilities, eight children (11.1%) presented MIH with 19 affected teeth. In the control group, one child (1.4%) presented MIH with two affected teeth. The difference was statistically significant (p = 0.033). There were no statistically significant differences between boys and girls. The molars, especially the first right molars were the most affected tooth. Brown defects were less common than white defects.

CONCLUSION

Children with MIH should be identified because this condition is a common problem in children with intellectual disabilities.

Molar incisor hypomineralization (MIH): prevalence and degree of severity in a Mexican pediatric population living in an endemic fluorosis area

OBJECTIVE

To estimate the prevalence and severity of molar incisor hypomineralization (MIH) in 8 years old children living in an endemic fluorosis area.

METHODS

MIH prevalence rate was determined from a study sample comprising 613 participants. They were recruited from 11 urban public schools with similar socio-economic status. Oral evaluations were performed and diagnosed MIH teeth were classified under Ghanim et al.'s criteria. Statistical descriptive and comparative analyzes were carried out.

RESULTS

First permanent molars were the tooth group most affected, followed by the upper central incisors, lower central incisors, lower lateral incisors, and upper lateral incisors. There was no significant statistical difference by gender and by maxillary/mandible arches (P = 0.82 and 0.26, respectively). The frequency of MIH was more in molars compared to incisors (P < 0.02).

CONCLUSIONS

The MIH prevalence in this study was 12.4 percent. According to the MIH severity, degree 2 was the most frequently detected (76.4 percent).

100 Years of Chalky Teeth Research: From Pioneering Histopathology to Social Good

One hundred years ago, histopathology pioneer Bernhard Gottlieb described developmentally disrupted teeth as having “chalky enamel” and “chalky spots” that “crumble” easily. He also asked pivotal questions about the pathogenesis of “enamel hypoplasia” that remained enigmatic for almost a century. Today, breakthrough pathomechanistic investigations of chalky enamel are revealing surprising answers, and an allied translational initiative—The D3 Group for developmental dental defects (“D3s”) —is converting such scientific knowledge into social good surrounding prevention of tooth decay. Molar hypomineralisation (MH) affects 1-in-5 children worldwide and is well-evidenced, but poorly recognised, as a principal risk factor for childhood tooth decay. Given MH is causally linked to infantile illness, an exciting corollary is that medical prevention would lead to substantial reductions in decay. Here we reflect on the past century of chalky teeth research and retrace the path leading to recognition of MH as a global health concern. Five research eras, today's four major D3s, and diverse experimental attacks are outlined alongside translational wins that have benefitted global health. Addressing hopes for medical prevention of MH, this centennial year's pathomechanistic discovery is contextualised against past accomplishments and new opportunities. Finally, we note the translational value of accessible infographics for guiding future work, and forecast exciting prospects for the next century.

Molar-incisor hypomineralization in quilombola children and adolescents: A study of prevalence and associated factors

OBJECTIVES

This cross-sectional observational study determined the prevalence and factors associated with molar-incisive hypomineralization (MIH) in quilombola children and adolescents in north-eastern Brazil.

METHODS

The sample consisted of 251 children and adolescents (8 to 14 years old) living in the rural quilombola community Lagoas in São Raimundo Nonato, Piauí (census population). Sociodemographic and health-related data were collected from pre-, peri- and post-natal health records and a clinical examination for MIH diagnosis was performed by four previously trained and calibrated examiners. Descriptive data analysis and Poisson regression were performed. The magnitude of the association was determined by adjusted prevalence ratio (PR) and confidence intervals (95% CI).

RESULTS

The prevalence of MIH was 46.6%. The presence of MIH was associated with gestational diabetes (PR = 2.49, 95% CI 2.08-2.99; p <0.001) and acute foetal distress (PR = 1.39; 95% CI 1.04-1.86; p = 0.025).

CONCLUSION

It was concluded that the prevalence of MIH in the quilombola community was high and associated with gestational diabetes and acute foetal distress.

The possible influence of genetic aetiological factors on molar-incisor hypomineralisation

OBJECTIVE

The present study searched for evidence of possible associations between some genetic factors that could affect the development of molar-incisor hypomineralisation (MIH).

METHODS

In 113 patients who were surgically treated at an Otorhinolaryngology and Cervicofacial Surgery Clinic (ORL) during early childhood, human leukocyte antigen (HLA) DQ2 and DQ8 haplotypes and single nucleotide polymorphisms (SNP) of eight amelogenesis-related genes were searched in genomic DNA. Genotypes were determined by high resolution melting (HRM), TaqMan genotyping assays, and Sanger sequencing. Association between MIH and the HLA DQ2 and DQ8 alleles was tested using a univariate logistic regression. The significance of genetic variants was analysed using the Cochran-Armitage tests for trend and the Fisher exact tests.

RESULTS

We identified MIH in 22 (19.5 %) of the 113 children. Among the evaluated genetic variants, SNP rs2245803 in the MMP20 gene in a homozygous form in a recessive model was associated with MIH development (OR, 2.796; 95 %CI, 1.075 - 4.783; p = 0.0496) with the genotype distribution of TT(3), TG(6) or GG(13) in children with MIH and distribution of TT(18), TG(42) or GG(31) in children without MIH.

CONCLUSIONS

While the aetiology of MIH remains unclear, our findings suggest that variants of genes associated with amelogenesis may play important roles in susceptibility to MIH.

Prevalence of molar-incisor hypomineralization and other enamel defects and associated sociodemographic determinants in Indiana

BACKGROUND

The aim of this study was to determine the prevalence and severity of molar-incisor hypomineralization (MIH) in a cohort of school-aged children in Indiana.

METHODS

A calibrated examiner screened eligible school-aged children for MIH and other enamel defects. The authors used the integrated Modified Developmental Defects of Enamel Index and the European Academy of Pediatric Dentistry criteria to examine the permanent first molars, permanent incisors, and primary second molars. The authors used descriptive statistics, exact 95% confidence intervals, and χ² tests for analysis (α = 5%).

RESULTS

A total of 337 participants (mean [standard deviation] age, 9.1 (1.7) years; 52% 6 through 8 years; 66% non-Hispanic white) were examined. The prevalence estimate for MIH was 13% as opposed to a 52% prevalence estimate for any enamel defect (AED) of any of the index teeth. Living in an area with water fluoridation levels greater than 0.7 parts per million or being non-Hispanic black was significantly associated with higher prevalence of AED (P < .05) but not with the prevalence of MIH. Demarcated opacities were the most prevalent defects (43%), followed by atypical restorations (32%). Higher age and higher number of MIH-affected surfaces were associated with larger MIH defect extension (P < .05).

CONCLUSIONS

Nearly 1 in 6 children in Indiana had at least 1 permanent first molar with MIH. Water fluoridation levels and race or ethnicity were associated with the prevalence of AED but not with MIH prevalence.

PRACTICAL IMPLICATIONS

US dental practitioners should be cognizant that MIH is a common finding. Children with a high number of MIH-affected surfaces would benefit the most from early identification and management as the extension of the defects tends to worsen with age.

Molar incisor hypomineralisation and dental anomalies: A random or real association?

BACKGROUND

Clinical observations suggest molar incisor hypomineralisation (MIH) may present with other dental conditions.

AIMS

The study aimed to determine the prevalence and variety of dental anomalies in children presenting with MIH.

DESIGN

A convenience sample of children referred to a UK dental hospital was recruited. Orthopantogram radiographs, taken as part of routine care, were assessed for dental anomalies. Two calibrated examiners reviewed the films separately and determined the presence and character of anomalies.

RESULTS

Radiographs were obtained from 101 patients, with an age range of 6-15 years. Co-existing hypodontia was identified in 12%, with lower second premolars being the most commonly missing teeth. Concurrent ectopic first permanent molars were identified in 8%, and infraocclusion of one or more primary molars was identified in 9%. Abnormal morphology was found in 9%, including macrodont and microdont teeth. In total, 29% of patients had an associated dental anomaly. Examiners had perfect agreement using Cohen's kappa coefficient.

CONCLUSION

This high prevalence of dental anomalies, particularly hypodontia, in children with MIH is a novel and clinically important finding. Further research is warranted considering the potential implications for assessment and treatment planning.