Canines are affected in 16-year-olds with molar–incisor hypomineralisation (MIH): an epidemiological study based on the Tromsø study: "Fit Futures"

Comparative clinical performance of stainless steel, zirconia, and Bioflx crowns in primary molars: a randomized controlled trial

BACKGROUND

Choosing the appropriate crown type for primary molars is essential for effective restoration and oral health. Stainless steel crowns are durable and cost-effective, making them suitable for extensive decay. Zirconia crowns offer esthetic advantages, while Bioflx crowns require less preparation and provide optimal appearance. Understanding the benefits and limitations of each type ensures optimal outcomes for young patients. The purpose of the study was to clinically compare these three types of crowns for primary molars regarding plaque accumulation, debonding rate, crown substance loss and gingival health.

MATERIALS AND METHODS

Registered with clinicalTrials.gov (NCT06706167), this study included 75 children (43 males, 32 females; mean age: 6.3 years) divided into 3 groups: Group A (stainless steel crowns), Group B (zirconia crowns), and Group C (Bioflx crowns), with 25 patients each. Plaque index, crown survival regarding debonding rate and substance loss, and gingival index were evaluated at baseline, 6, and 12 months.

RESULTS

At 6- and 12-month follow-ups, no significant differences were observed among groups. However, zirconia crown demonstrated better results in terms of plaque accumulation and gingival health. Conversely, stainless steel crown showed marginally better performance in crown retention.

CONCLUSION

All crowns showed acceptable clinical performance. Factors such as crown retention, esthetics and biocompatibility should be considered when selecting the most appropriate crown for each molar.

TRIAL REGISTRATION

The study was registered on ClinicalTrials.gov, with the registration number NCT06706167 with registration date 26,112,024.

Knowledge, and treatment of molar incisor hypomineralisation (MIH) among dentists in Jordan: a cross-sectional questionnaire based study

AIM

The aim of this study is to assess the knowledge, and treatment of MIH among dentists in Jordan.

METHODS

An online questionnaire using Google Forms was sent to the dentists who were registered with the Jordan Dental Association and worked in Jordan through social media groups. The questionnaire consisted of three sections, sociodemographic characteristics, the knowledge of dentists about the aetiology, diagnosis, and prevalence of MIH, and treatment options and barriers for treating MIH. Descriptive statistics with chi-squared test was used, and level of statistical significance was set to 5%.

RESULTS

A total of 388 dentists had responded to the questionnaire (response rate 24.25%), (80.7%) reported that they have come across MIH cases during their practice. Yellow/brown demarcations were reported as the most common presentation of MIH (45.6%). All paediatric dentists were confident in diagnosing MIH, this was statistically higher than that reported by general dentists (56.8%) and dentists of other specialities (60.2%), P = 0.000. Pre-formed metal crowns were the treatment of choice for (57.2%) of participant, followed by composite restorations (52.3%). Child behaviour (56.2%), and late acknowledgment of the defect by the parents (46.1%) were the most encountered barriers for treatment.

CONCLUSION

Molar incisor hypomineralisation is a common condition that is encountered frequently by general dental practitioners as well as dental specialists, nevertheless most dentists were not aware about the prevalence of MIH in Jordan and indicated their need to improve their approach regarding MIH diagnosis and treatment.

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.

Prenatal exposure to environmental toxins and comprehensive dental findings in a population cohort of children

Environmental toxins are known to have many impacts on growth and development in humans, starting in utero. Alterations in amelogenesis, caused by chemical and physical trauma that occur during the antenatal, perinatal and postnatal time periods, may result in developmental defects in deciduous and permanent tooth enamel, as demonstrated in animal studies. These defects can be clinically visible and result in a variety of morphological and functional problems in the dentition. Since enamel does not remodel after formation, it may serve as a permanent record of insults during organ development.Our primary purpose was to investigate any possible relationship between intrauterine exposure to endocrine disrupting chemicals (phenols and phthalates) and developmental defects in enamel in children, while also accounting for fluoride exposure. Our secondary purpose was to report descriptively on findings from comprehensive dental examinations performed on 356 children that were drawn from the general paediatric population. A cohort of children from the Utah Children's Project (N = 356) that had full medical exams, comprehensive medical and family histories and available biospecimens were given extraoral and intraoral examinations. They also completed an oral health questionnaire. Standardized intraoral photographs were taken of the teeth and viewed by standardised examiners and the dental observations were recorded for a full inventory of findings, including: tooth morphology, caries, restorations, colorations, attrition, erosion, fractures and hypomineralization. Perinatal maternal urine samples were assessed for the concentration of fluoride, phenols and phthalates, including bisphenol A (BPA).Pairwise statistical analyses were done to correlate the dental findings with one another and with the presence of environment chemicals found in the urine samples. Hypomineralization was the most common finding (96% of children; 37% of deciduous teeth, 42% of permanent teeth), consistent with molar incisor hypomineralization (MIH) described in other human populations. No consistent correlations were seen between dental findings and the presence of phenols and phthalates in prenatal urine, but the number of samples available for the assessment was limited (n = 35).In conclusion, we found a high proportion of dental hypomineralization in a population based paediatric cohort, but did not find an association with prenatal exposure to phenols and phthalates.

Molar-Incisor Hypomineralisation: Severity, caries and hypersensitivity

OBJECTIVES

To investigate distribution of affected teeth and severity of molar-incisor hypomineralisation (MIH) in 8-9-year-old children. A second aim was to study association between severity of MIH and hypersensitivity, caries, and affection of incisors and second primary molars (SPM).

METHODS

A total of 3013 children in one age cohort participated in a cross-sectional study, of which 851 children were diagnosed with MIH. A majority of these children were re-examined and MIH diagnosis based on the European Academy of Paediatric Dentistry criteria was confirmed in 538 children. The re-examinations were undertaken at the local clinics by one calibrated dentist. Data were tested with bivariate logistic regression analysis. Results were reported using frequencies, proportions, odds ratios (OR) and confidence intervals (CI).

RESULTS

Almost half of the children with MIH (46.8 %) had at least one severely affected molar. Incisors were affected in 51.9 % of children with MIH, and the prevalence was higher in children with severe affection (57.4 %, p < 0.01). Among children with MIH, second primary molars were affected in 29.6 %, hypersensitivity in at least one first permanent molar was reported by 25.8 and 30.8 % had caries extending to dentine. Children classified with severe MIH were more likely to suffer from hypersensitivity (OR 5.62, 95 % CI 3.61-8.74) and dentine caries (OR 10.32, 95 % CI 6.46-16.50) than children with mild MIH.

CONCLUSION

Prevalence of hypomineralised incisors and SPM were high in the studied children with MIH. Children with severe MIH had higher probability of incisor affection, dentin caries and hypersensitivity.

CLINICAL SIGNIFICANCE

This study highlights the importance of understanding the association between MIH, caries and hypersensitivity, especially in children with severe MIH. These children need extensive and individualized care in the dental services to prevent caries and pain.

Is there a rise of prevalence for Molar Incisor Hypomineralization? A meta-analysis of published data

Since Molar Incisor Hypomineralization was first described as a pathologic entity, public perception often suggests a considerable rise in prevalence of the respective disease. Since there are still considerable doubts regarding the etiology and-accordingly-prevention of MIH and respective therapeutic approaches are difficult this question is of considerable clinical and public interest. Accordingly, a systematic literature search in accordance with the PRISMA guidelines for systematic reviews on Medline, Cochrane Database, EMBASE, LILACS, Web of Science, Google scholar, Scopus was performed to retrieve original articles reporting the prevalence of MIH as defined by the European Academy of Pediatric Dentistry (EAPD). From initially 2360 retrieved titles, 344 full texts were assessed for possible inclusion and finally 167 articles of mainly moderate to high quality and based on data of 46'613 individuals were included in the meta-analysis. All studies published before 2001 had to be excluded since it was not possible to align the findings with the EAPD classification. Studies varied considerably regarding cohort size (25 to 23'320, mean 1'235)) and age (5.6-19 y, mean 9.8 y). Over all studies, the weighted mean for the prevalence for MIH was 12.8% (95% CI 11.5%-14.1%) and no significant changes with respect to either publication year or birthyear were found. A sub-analysis of eleven studies reporting on the prevalence in different age groups, however, revealed strong evidence for an increasing prevalence between the years 1992 (3%) and 2013 (13%).Therefore, based on data from cross-sectional studies a possible rise in prevalence of MIH remains unclear. Future prospective large-scale studies under standardized examination conditions with an emphasis on examiner calibration are needed to gain better understanding in the evolution of the prevalence of MIH.

Prevalence and severity of molar-incisor hypomineralization, is there an association with socioeconomic status? A cross-sectional study in Chilean schoolchildren

PURPOSE

Data about molar-incisor hypomineralization (MIH) prevalence and its severity remains limited for some Latin American countries. Furthermore, its association with socioeconomic status (SES) is still unclear. Thus, this study aims to determine the prevalence and severity of MIH in Santiago, Chile and explore its association with SES.

METHODS

A cross-sectional study with schoolchildren between 6 and 12 years was conducted. Children were evaluated using the European Academy of Paediatric Dentistry to diagnose MIH, and the Mathu-Muju and Wright criteria to determine its severity.

RESULTS

A total of 1,270 children were included. The MIH prevalence was 12.8% without association with gender (p = 0.609). Prevalence was higher among schoolchildren ages 8 and 9 (p = 0.002), and in lower SES (p = 0.007). MIH mild cases were the most prevalent (63%), and severity was not related to gender (p = 0.656), age (p = 0.060), or SES (p = 0.174).

CONCLUSIONS

The prevalence of MIH in the province of Santiago, Chile is 12.8% and was found to have a higher incidence in 8-9-year-old students and among those categorized by low SES. Furthermore, MIH prevalence was associated with low SES.

IMPLICATIONS

Public health policies to address MIH in Chile should start with schoolchildren aged 8 to 9, and with low SES.

Association of dental hypersensitivity and anxiety in children with molar-incisor hypomineralisation (MIH)

AIM

The objective of this study was to investigate whether dental hypersensitivity and dental fear were linked to the presence and severity of MIH.

METHODS

For this cross-sectional study, 1830 students between the ages of 6 and 12 years were recruited from four randomly selected schools. The Children's Fear Survey Schedule-Dental Subscale questionnaire was used to assess dental anxiety and fear. The children's self-reported dental hypersensitivity resulting from MIH was evaluated using the Wong-Baker Facial Scale and the Visual Analog Scale (VAS).

RESULTS

MIH was correlated with tooth hypersensitivity, particularly in severe cases. Dental fear was present in 17.4% of the children with MIH, but it was not associated with dental hypersensitivity, gender, or age.

CONCLUSION

No association was found between dental fear and dental hypersensitivity in children with MIH.

Study on machine learning of molar incisor hypomineralization in an endemic fluorosis region in central China

Objectives: The aim of the present study was to develop a machine learning model to predict the risk of molar incisor hypomineralization (MIH) and to identify factors associated with MIH in an endemic fluorosis region in central China.

Methods: A cross-sectional study was conducted with 1,568 schoolchildren from selected regions. The clinical examination included an investigation of MIH based on the European Academy of Paediatric Dentistry (EAPD) criteria. In this study, supervised machine learning (e.g., logistic regression) and correlation analysis (e.g., Spearman correlation analysis) were used for classification and prediction.

Results: The overall prevalence of MIH was 13.7%. The nomograph showed that non-dental fluorosis (DF) had a considerable influence on the early occurrence of MIH and that this influence became weaker as DF severity increased. We examined the association between MIH and DF and found that DF had a protective correlation with MIH; the protective effect became stronger as DF severity increased. Furthermore, children with defective enamel were more likely to experience caries, and dental caries were positively correlated with MIH (OR = 1.843; 95% CI: 1.260–2.694). However, gender, oral hygiene, and exposure to poor-quality shallow underground water did not increase the likelihood of developing MIH.

Conclusions: DF should be considered a protective factor within the multifactorial etiology of MIH.

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.

Molar-Incisor Hypomineralization: Prevalence Comparative Study in 6 Years of Interval

The aim of this study was to evaluate the prevalence evolution rate of MIH (molar-incisor hypomineralization) after a 6-year period in Araraquara/SP, Brazil. This population-based study evaluated MIH in 545 schoolchildren (6-12 years of age) and other associated alterations, dental caries and dental fluorosis (DF). A semistructured questionnaire was sent to the schoolchildren's parents/guardians with the purpose of identifying the socioeconomic profile. Associations between MIH and the clinical characteristics were analyzed by the Poisson analysis of regression with robust variance, estimating the RPc (crude prevalence ratio) with CI 95%. The level of significance of 5% was adopted. The MIH prevalence in Araraquara/SP in 2016 was 14.3% (n = 78), and at this time, an increase of 2% was observed, in comparison with the data of the first prevalence study conducted in 2010 (12.3%). The mild degree compromise was the most prevalent diagnosis in the affected teeth (82.0%). Among children with MIH, the mean number of affected teeth was 2.78. Of the total number of children with MIH, 32.0% presented alterations in both first permanent molars and permanent incisors. There is no significant association between MIH and dental caries experience on permanent dentition (PRc = 1.141; CI 95% 0.709-1.835) or on primary dentition (PR c  = 1.132; CI 95% 0.749-1.709). Children with MIH presented significantly less prevalence of dental fluorosis (PR c  = 0.505; CI 95% 0.268-0.950). There is no association between MIH and monthly Brazilian minimal wage income (PR c  = 1.130; CI 95% 0.655-1.949). It was concluded that the number of MIH cases had increased, revealing a greater need for defining the etiological factors and establishing a correct diagnosis to make it possible to institute early intervention.

Maternal vitamin D status in pregnancy and molar incisor hypomineralisation and hypomineralised second primary molars in the offspring at 7-9 years of age: a longitudinal study

Purpose

The study aimed to investigate associations between maternal vitamin D status during pregnancy and molar incisor hypomineralisation (MIH) and hypomineralised second primary molars (HSPM) among children.

Methods

The study had a longitudinal design using prospectively collected data from 176 mother and child pairs. Mothers were initially recruited in a randomised controlled trial to assess a pregnancy exercise programme. Along with the 7-year follow-up, we invited the children to a dental examination. The exposure variable was maternal serum 25-hydroxyvitamin D in gestational weeks 18–22 and 32–36, categorised as insufficient (< 50 nmol/l) and sufficient (≥ 50 nmol/l). Negative binomial hurdle models were used to analyse potential associations between the exposure variables and MIH or HSPM. The models were adjusted for potential confounders.

Results

Among the children (7–9 years old), 32% and 22% had at least one tooth with MIH or HSPM, respectively. A significant association was found between insufficient maternal vitamin D measured in gestational weeks 18–22 and the number of affected teeth among those with MIH at 7–9 years (adjusted RR = 1.82, 95% CI 1.13–2.93).

Conclusion

Considering any limitations of the present study, it has been shown that insufficient maternal serum vitamin D at mid-pregnancy was associated with a higher number of affected teeth among the offspring with MIH at 7–9 years of age. Further prospective studies are needed to investigate whether this finding is replicable and to clarify the role of maternal vitamin D status during pregnancy and MIH, as well as HSPM, in children.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40368-022-00712-y.

Prevalence, Pattern, and Severity of Molar Incisor Hypomineralization in 8-12-year-old Schoolchildren of Moradabad City

AIM AND OBJECTIVE

Recently, molar incisor hypomineralization (MIH) has become more evident and one of the most common reasons for loss of teeth in children after dental caries. Being a country with a diverse ethnic population, the prevalence of MIH in different regions of India may differ. Hence, the present study was undertaken to determine the prevalence, pattern, and severity of MIH in 8-12-year-old Schoolchildren in Moradabad city.

MATERIALS AND METHODS

This study was conducted in various schools of Moradabad city to target a sample of 2,300 children aged between 8 and 12 years. The examination was done in their respective schools by a calibrated examiner in natural daylight using European Academy of Pediatric Dentistry diagnostic criteria for MIH 2015. The results, thus obtained, were statistically analyzed using Pearson's Chi-square test.

RESULTS

A prevalence of 3.96% (91/2300) for MIH was reported without any gender predilection. Molar hypomineralization showed a prevalence of 1.3% (29/2300) whereas the prevalence for hypomineralization of second primary molars was 1.4% (22/1620). The most common type of defect was type 2 and most of the affected teeth were of grade I. Mandibular molars were more commonly affected compared to the maxillary molars.

CONCLUSIONS

A prevalence of 3.96% (91/2300) was observed for MIH. Frequent dental screening camps should be organized in schools at the community level for the enhancement of early diagnosis of MIH and designing appropriate management strategies.

HOW TO CITE THIS ARTICLE

Khan A, Garg N, Mayall SS, et al. Prevalence, Pattern, and Severity of Molar Incisor Hypomineralization in 8-12-year-old Schoolchildren of Moradabad City. Int J Clin Pediatr Dent 2022;15(2):168-174.

Molar-incisor hypomineralisation: an updated view for aetiology 20 years later

BACKGROUND

The term Molar-Incisor Hypomineralisation (MIH) was introduced in 2001 by Weerheijm, Jälevik and Alaluusua, and describes a defect of systemic origin that affects one to four first permanent molars, often associated with permanent incisors. In the past 20 years, this definition dictated the work regarding MIH prevalence, associated risk factors, association with dental caries, impact on quality of life, and therapeutic options.

PURPOSE

In this report, we offer an updated and comprehensive view of MIH centred on the patient and the tooth.

CONCLUSION

MIH today is globally recognized as a potential public health problem and it is not a defect of purely systemic origin but rather a condition with complex aetiology that in some instances may be the result of gene-environmental interactions.

Extraction of first permanent molars severely affected by molar incisor hypomineralisation: a retrospective audit

AIM

The aim of this study was to evaluate possible spontaneous space closure after extraction of first permanent molars in children and their eventual need for orthodontic treatment.

METHODS

Twenty-seven children with at least one first permanent molar planned for extraction were enrolled in the study. The children were referred to the Department of Paediatric Dentistry, University of Oslo, between 2009 and 2017. All extracted teeth were severely affected by Molar Incisor Hypomineralisation and/or caries. The children and their parents had consented to extraction and follow-up. Data were analysed with SPSS 26.

RESULTS

The age of the children was between 5.5 and 12.1 years (mean 8.7) at extraction. The mean follow-up time was 3.2 years (range 1.1-6.3). Sixteen children (59.3%) had all four molars extracted, five (18.5%) had three, five had two and one had one molar extracted. In the maxilla, the second permanent molar had erupted in the place of the first molar in all the children, and none of them needed orthodontic space closure. In the mandible, eight children (29.6%) needed orthodontic treatment to close the spaces after extraction. In three children, the second molar was not yet erupted and treatment need was not settled.

CONCLUSION

Extraction of severely affected first permanent molars before the eruption of the second molar is a treatment option causing little additional treatment in the majority of cases.

Effects of antibiotics on the developing enamel in neonatal mice

PURPOSE

Identifying factors causing Molar-Incisor Hypomineralization (MIH) is an ongoing challenge. Preterm infants, routinely treated with antibiotics in cases of suspected sepsis, are more commonly affected by dental developmental defects. This study aimed to investigate the effects of gentamycin and ampicillin on the developing enamel in neonatal CD-1 mice in vivo.

METHODS

Neonatal mice were randomized into a study (n = 36) and a control (n = 35) group. Antibiotics were injected intravenously for 4 days. All mice were sacrificed after 15-18 days. Micro-CT was used to analyse the mineral density (MD) of the enamel and the proportion of the enamel object volume (vol%) in first molars and incisors.

RESULTS

We demonstrated a significantly lower vol% enamel in the maxillary (30.9% vs. 32.7%; p = 0.004) and mandibular (32.5% vs. 34.6%; p = 0.015) molars in the study group than in the controls. The incisors were divided into segments upon analysis. We demonstrated both lower vol% and lower MD of the enamel in most segments in treated individuals compared to controls (p < 0.05).

CONCLUSION

The reduced MD and vol% in the molars and incisors are likely to have been caused by the antibiotics given during tooth development. The presented analysis of teeth in neonatal mice with micro-CT could be a valid model for further research on dental developmental defects.

Does molar-incisor hypomineralization (MIH) affect only permanent first molars and incisors? New observations on permanent second molars

BACKGROUND

The second permanent molar plays an important role when considering extraction of first permanent molars severely affected by molar-incisor hypomineralization (MIH).

AIM

To assess the association between MIH and enamel hypomineralization of the second permanent molars in terms of presence and severity.

DESIGN

In this retrospective cross-sectional study, permanent teeth were evaluated in 453 patients between the ages of 13 and 16 at a dental clinic, using intraoral photographs. A calibrated examiner classified enamel hypomineralization using the MIH index and dental caries experience using the DMFT and DMFS indices. Statistical analyses were performed using a linear generalized model and ordinal logistic regression.

RESULTS

The most commonly affected teeth by enamel hypomineralization were permanent molars, whereas incisors, premolars, and canines were less affected. The presence of severe defects in the first permanent molars was associated with mild defects in the second permanent molars (OR = 4.01; 95% CI: 2.50-7.77). Enamel hypomineralization was associated with increased caries experience (PR = 5.54; 95% CI: 3.81-9.06).

CONCLUSION

Enamel hypomineralization mainly affects the first and second permanent molars. Mild defects in the second permanent molars tend to be more frequent in patients with severe MIH in the first permanent molars. The presence of enamel hypomineralization was associated with higher dental caries experience.

The prevalence of molar-incisor hypomineralization: a systematic review and meta-analysis

Molar-Incisor Hypomineralization (MIH) is a qualitative defect of enamel of unknown etiology, affecting one or more permanent molars and may include incisors. This condition is a clinical challenge and its prevalence is still uncertain given the recent increase in research. Thus, we aimed to comprehensively estimate the overall prevalence of MIH and associated characteristics. This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). We searched articles using PubMed, MEDLINE, CENTRAL, Web of Science, SciELO, LILACS and TRIP databases, until July 2021. Heterogeneity and publication bias were computed via I2 test statistics and Egger's significance test, respectively. Random-effects meta-analysis of prevalence were processed. We used the Strength of Recommendation Taxonomy [SORT] to grading the strength of evidence. Overall, 116 observational studies were included, with one study with moderate methodological quality and the remaining of high methodological quality. Subgroup analysis confirmed an influence of not using the 2003 MIH case definition (p = 0.0066). The pooled prevalence of MIH was 13.5% (95% CI 12.0-15.1, I2 = 98.0%). Affected incisors were seen in 36.6% (95% CI 30.0-43.7, I2 = 92.5%) of the cases. Lastly, the prevalence of hypomineralization of the second primary molars was observed in 3.6% of the MIH cases (95% CI 1.9-6.8, I2 = 96.3%). America was the continent with highest prevalence (15.3, 95% CI 12.8-18.3, p < 0.001, I2 = 96.3%) and Asia had the lowest prevalence (10.7, 95% CI 8.5-13.5, p < 0.001, I2 = 98.7%), however no continental differences were found. Sample size and year of publication were slight contributing factors to the heterogeneity in the analysis. Overall, these results were classified with a SORT A recommendation.

Knowledge, experience and perception regarding molar incisor hypomineralisation (MIH) among dentists and dental hygienists in Oslo, Norway

Aim

The aim of this study is to gather baseline information on knowledge, perceptions, clinical experience and treatment options regarding MIH among dental care providers in Oslo, Norway, before a larger epidemiological study.

Methods

An electronic questionnaire was distributed to dentists (n = 88) and dental hygienists (n = 47) working in the Public Dental Service (PDS) in Oslo. The questionnaire consisted of five sections related to sociodemographic, clinical experience, perceptions, clinical management and preferences for further training. Descriptive statistics with chi-squared test was used, and level of statistical significance was set to 5%.

Results

Replies were obtained from 74.1% (n = 100) after two reminders. All respondents encountered MIH in their practice. The respondents’ perception of the prevalence of MIH in Oslo varied. The majority felt confident when diagnosing MIH (86%). The clinicians qualified in the last 10 years felt more confident than those who had qualified earlier (p = 0.016). Most were self-confident when treating these patients (68.3%), however, nearly all (88%) agreed that MIH was a clinical problem. The clinician’s treatment of MIH varied. Difficulties achieving adequate local anaesthetic (71.4%) and the child’s behavioural problems (84.1%) were treatment barriers for the dentists. Approximately two thirds (69%) would like further training, in particular on the aetiology (70%), diagnosis (57%) and treatment (77%) of the developmental disorder.

Conclusion

All clinicians were familiar with the diagnosis of MIH and experienced the condition to be a clinical problem. Continuing education on aetiology, diagnosis and treatment of MIH is requested by dental health personnel.

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.

Molar-incisor hypomineralization (MIH), dental fluorosis, and caries in rural areas with different fluoride levels in the drinking water

AIM

This study determined the prevalence of molar-incisor hypomineralization (MIH) and its association with dental fluorosis and caries in children living in rural areas in north-eastern Brazil who are exposed to residual fluoride (F) levels in the drinking water.

DESIGN

A census was carried out with 610 schoolchildren aged 6 to 12 years. The European Academy of Paediatric Dentistry criteria, Thysltrup and Fejerskov index, and World Health Organization index were used for diagnosis of MIH, dental fluorosis, and caries detection, respectively. The association between the outcome and exposure variables was determined by robust Poisson regression (P < .05).

RESULTS

Water F-levels varied from 0.06 to 1.98 ppm. MIH was not related to fluoride levels in the drinking water, but it showed an inverse and direct correlation with dental caries and fluorosis, respectively. Children with MIH had a higher DMFT, and severe MIH cases were most frequent in children with dental fluorosis.

CONCLUSION

Drinking water F-levels were not directly related to the occurrence of MIH in schoolchildren. The severity of MIH, however, was likely to be associated with dental fluorosis in areas with moderate to high fluoride levels in the drinking water.

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 (MIH) in a Child with Congenital Chronic Intestinal Pseudoobstruction (CIPO)

Molar incisor hypomineralization (MIH) is a qualitative enamel defect of systemic origin affecting 1-4 permanent first molars (PFMs) frequently in association with affected permanent incisors (PIs). The exact etiology of MIH is still unclear but considered to be multifactorial. This present case report to the best of our knowledge is the first case reported which acknowledges MIH in a patient with chronic intestinal pseudoobstruction (CIPO) with underlying neurological disease due to somatic mitochondrial disorder. It also elicits the availability of various contemporary treatment options and their proper selection and early intervention to manage the functional and aesthetic problems caused by enamel defects and to improve the quality of life in the patients.

Molar incisor hypomineralization, prevalence, pattern and distribution in Sudanese children

BACKGROUND

Molar incisor hypomineralization (MIH) has serious impact on oral health-related quality of life for a child, due to its effects on tooth structure, aesthetics and behavior of the child. The current study was designed to determine the prevalence, pattern and distribution of MIH in school children in Sudan.

METHODS

This was a descriptive cross-sectional study involving 568 children, aged 8-11 years from schools in Khartoum State. Following the collection of their socio-demographic data, the children were examined for hypomineralization on the 12 MIH-index teeth, the pattern and distribution of the MIH. The data collected was analyzed to obtain descriptive statistics. The results related to the socio-demography and other dental-related factors were tested using chi-square test and Spearman Rank Correlation, with the significant level set at p < 0.05.

RESULTS

The prevalence of MIH in the study population was 20.1%. The majority of the participants had both permanent first molars (PFMs) and permanent incisors affected (12.5%). However, in 7.6% of the cases only molars were affected. Even though more maxillary teeth were affected when compared to the mandibular teeth, there was no statistical significant difference between the occurrence of hypomineralization on mandibular and maxillary molars (p = 0.22). Maxillary incisors were significantly more affected by MIH when related to the mandibular ones (p = 0.00). Demarcated opacities were the commonest pattern of MIH defects (69.9%) in the experimental group.

CONCLUSION

The prevalence of MIH in Sudanese children was 20.1%. In both dental arches, the permanent molars and incisors were frequently affected, with the demarcated opacity type of MIH being the most common form of defect.

Use of asthma drugs and prevalence of molar incisor hypomineralization

BACKGROUND

Asthma and molar incisor hypomineralization (MIH) are common diseases among children and have been suspected to be associated with each other.

AIM

To examine the association between asthma or the use of asthma drugs and the prevalence of MIH.

DESIGN

In a population-based cross-sectional study, we recorded MIH in 9-year-old children in Aalborg Municipality, Denmark, born in the year 2000. We used a unique 10-digit civil personal number to link data on MIH to population-based medical register data. The exposure was inhaled asthma medication from birth date until date of dental examination. The outcome was the overall prevalence of MIH according to use of asthma medication. Odds ratios (OR) of having MIH were adjusted for gender, use of antibiotics and amoxicillin, maternal smoking, pre- and perinatal complication, and hospital admissions.

RESULTS

We examined 1837 children, of which 542 (29.5%) had one or more molar(s) with MIH. The adjusted odds ratio of having MIH was 0.95 (95% CI: 0.60-1.51) among children with prescriptions of inhaled asthma medication.

CONCLUSION

In this study, where the results have been adjusted for confounding, we found no association between use of inhaled asthma medication and the prevalence of MIH.

Estimating molar-incisor-hypomineralization among 8-year-olds based on 15-year public oral health practice-based data

Background: A wide range in the prevalence of molar-incisor-hypomineralization (MIH) has been reported. Population-based studies are recommended. However, such studies are expensive and time-consuming.Objectives: To estimate the magnitude of MIH condition among 8-year-olds based on routine oral health examinations and to associate first permanent molar (FPM) affection with that of other permanent teeth over time.Materials and methods: This retrospective study, with cross-sectional and longitudinal components, was based on electronic oral health records; all 8-year-olds examined between 2002 and 2016 were included.Results: The average estimated prevalence of MIH was 8.3%; yearly range was 4.8-15.9%. The mean number of affected teeth was 1.4; 62% had one affected tooth. One-surface defects were the most frequent (66%). Asymmetric distribution of affected teeth was observed. In follow-up, 10.7%, 8.4%, and 11.2% had at least one affected permanent canine, premolar, or second permanent molar, respectively. The proportion of children with other MIH-affected permanent teeth was higher in the group with ≥2 MIH-affected teeth than in group with one affected FPM at the age of 8.Conclusions: The average prevalence of MIH was comparable to that reported elsewhere. The number of MIH-affected teeth at early mixed dentition predicts the affection of other permanent teeth over time, mainly that of permanent canines. Further screening of children with MIH is recommended to improve individually tailored early preventive and restorative dental care.

Molar Incisor Hypomineralisation-To Extract or to Restore beyond the Optimal Age?

The management of compromised first permanent molars (FPMs) in children presents a clinical challenge to the dental team. Hypomineralised FPMs in molar incisor hypomineralisation (MIH) conditions could undergo post-eruptive breakdown, making them susceptible to caries, leading to their subsequent loss. The planned extraction of compromised FPMs is a valid alternative to complex restorative treatment. However, establishing the presence or absence of third permanent molars, amongst other considerations, is crucial to reaching a successful outcome. Clinicians should understand the importance of an orthodontic examination around the age of 8 years old with regard to establishing a differential therapeutic decision about the ideal timing of MIH-affected FPMs’ extraction in children. The aim of this article is to highlight that, with an interdisciplinary approach, a good outcome can be achieved following the extraction of poorly prognosed FPMs. The most cost-effective way of addressing MIH-affected FPMs is extraction, followed by orthodontic space closure when indicated. This obviates the need for the repeated restorative replacement and saves perfectly healthy premolars from being extracted for space creation in orthodontic treatment in several clinical scenarios.

A Primary Care Randomized Controlled Trial of Hall and Conventional Restorative Techniques

OBJECTIVES

To investigate treatment outcomes of different restorative techniques undertaken by dental therapists for primary molar carious lesions in a sample of children in New Zealand primary care.

METHODS

This was a randomized controlled trial with children aged 3 to 8 y in New Zealand's Whanganui region. Children meeting inclusion criteria were randomly allocated to treatment with either the Hall technique (HT), in which a stainless-steel crown (SSC) is placed without any carious tissue removal or tooth preparation, or a non-Hall conventional restorative approach (NHT), including tooth preparation with selective carious tissue removal; this included SSC, amalgam, composite, or glass ionomer cement (GIC) restorations. Restorative outcomes after 12 and 24 mo were categorized as success, minor failure, or major failure.

RESULTS

Of the 295 eligible children, 149 and 146 were allocated to the HT and NHT groups, respectively, with a total of 570 carious primary molars treated by 13 dental therapists. The participant follow-up rates at 12 and 24 mo were 95% and 91%. SSCs were the most commonly used restoration in the NHT group (60%), followed by GIC (28%). SSCs were the most successful restorations regardless of whether they were placed with the HT or NHT, with success rates of 89% and 92% at 12 mo and 85% and 86% at 24 mo. In the NHT group, the treatment material was a predictor of minor failure at 12 and 24 mo, with significantly more failures with GICs.

CONCLUSIONS

SSCs placed by dental therapists are a highly successful restoration for the primary dentition, regardless of whether they are placed with the HT or conventionally. The high failure rate of glass ionomer restorations means that they cannot be recommended for widespread use in New Zealand primary care (Australian New Zealand Clinical Trials Registry, ACTRN12614000844640).

KNOWLEDGE TRANSFER STATEMENT

The findings of this study can be used by policy makers and clinicians when deciding on which materials and which approach to use to maximize success and to minimize retreatment rates when providing restorative treatment for carious primary molars in children's primary oral health care. Results also suggest that undertaking research in the primary care setting may enhance translation of new knowledge and techniques into clinicians' hands.

On the Variable Clinical Presentation of Molar-Incisor Hypomineralization

Molar-incisor hypomineralization (MIH) is a condition that is defined based on its peculiar clinical presentation. Original reports on the etiology of the condition and possible risk factors were inconclusive, and we refuted the original suggestion that MIH is an idiopathic condition and suggested that MIH has complex inheritance and is due to the interaction of more than one gene and the environment. Our group was the first to suggest MIH has a genetic component that involves genetic variation in genes expressed during dental enamel formation. Later we expanded this work to include genes related to the immune response. In this report, we provide a rationale to explain the variation seen in the clinical presentation of MIH, which can affect just one molar out of the four or just a portion of a particular molar.

Molar incisor hypomineralization and pre-eruptive intracoronal lesions in dentistry-diagnosis and treatment planning

The aim of this study is to report the diagnostic features, prevalence, mineral content, clinical significance and treatment options of molar incisor hypomineralization (MIH) and pre-eruptive intracoronal lesions (PEIR), in order to minimize miss-treatment of primary and permanent teeth in young children. MIH was defined as the occurrence of hypomineralization of one up to four permanent first molars from a systemic origin and frequently associated with affected incisors. PEIR are lesions that are located in the occlusal portion of the crown of unerupted permanent or primary teeth. The prevalence of MIH was reported between 2.5%-40% in the permanent first molars and 0%-21.8% in primary second molars. PEIR was observed in 2%-8% of children, mainly in mandibular second premolars and second and third permanent molars. A number of possible causes for MIH were mentioned, including environmental changes, diet and genetics in prenatal and postnatal periods, but all are questionable. In PEIR, the resorption of the intracoronal dentine begins only after crown development is complete and is caused by giant cells resembling osteoclast observed histologically on the dentine surface close to the pulp. The mineral content in MIH is reduced in comparison to normal enamel and dependent on the severity of the lesion. In PEIR the resorbed surface of enamel showed less mineral content. The hypomineralized enamel in MIH is not suitable for restorations with amalgam or composite materials, and the best material should be based on remineralization material like glass-ionomers. Similar, the resorbed dentin surface in PEIR should be covered by the biocompatible and re-mineralizing glass-ionomer cement.

BiodentineTM versus formocresol pulpotomy technique in primary molars: a 12-month randomized controlled clinical trial

BACKGROUND

The objective of this clinical study was to prospectively compare the clinical and radiographic success rates of BiodentineTM pulpotomies versus formocresol pulpotomies in children vital primary molars.

METHODS

A randomized, split-mouth study design was used with a sample of 37 healthy children aged 4- to 8-year-old. A total of 56 pairs (112 teeth) of carious primary teeth, 1 pair per child, were selected for treatment. One tooth from each pair was randomly assigned to either the BiodentineTM pulpotomy group or the formocresol pulpotomy group. Children were followed-up at 3, 6 and 12 months for clinical evaluation and at 6 and 12 months for radiographic evaluation. Data were collected, tabulated and analyzed using Fisher exact and McNemar tests. The level of significance was set at P < 0.05.

RESULTS

At 12 months, the clinical success rates of both BiodentineTM and formocresol groups were 100%, while the radiographic success rates for BiodentineTM and formocresol groups were 100% and 98.1%, respectively. There was no statistically significant difference between both groups (P=1). The only observed radiographic failure was furcal radiolucency in the formocresol group at 12-month interval. Pulp canal obliteration was radiographically observed in 10/56 (17.9%) and 7/56 (12.5%) cases in the BiodentineTM and formocresol groups, respectively.

CONCLUSIONS

Both BiodentineTM and formocresol pulpotomy techniques demonstrated favorable clinical and radiographic outcomes over a 12-month period without any significant difference.

TRIAL REGISTRATION

Registered on NCT03779698 . Date of Registration: 18 December 2018.

Molar incisor hypomineralisation (MIH) - an overview

Recent data indicates that molar-incisor hypomineralisation (MIH) is a frequently - encountered dental condition worldwide. The condition could be associated with dental complications that might affect patients' quality of life as well as create treatment challenges to dentists. The affected teeth are more prone to caries and post-eruptive enamel breakdown, therefore, it is believed that this condition might be responsible for a substantial proportion of childhood caries since the condition has high prevalence. MIH is common, and as such it should be diagnosed and managed in primary care wherever possible. Early diagnosis can lead to more effective and conservative management. This article aims to highlight different aspects related to MIH, from its prevalence to treatment options in young patients.

Prevalence and etiology of molar-incisor hypomineralization (MIH) in the city of Istanbul

Background/purpose

Molar-Incisor-Hypomineralisation (MIH) is the term used to depict a condition in which one or more of the permanent molar teeth and usually no less than one incisor tooth is hypomineralised and the prevalence rates vary from 2.4 to 40.2%. The aim of this study was to assess the prevalence and the risk factors of MIH in children in Istanbul, Turkey.

Materials and methods

A total of 1511 (760 M, 751 F), 8- to 11-year-old children were examined who had their first permanent molar and incisors evaluated using the EAPD criteria for MIH. Hypomineralized molars and incisors were recorded based on developmental defects of enamel index. The potential aetiological factors were retrieved through personal interview and etiological questions were asked to the parents. Statistical analysis was performed with a chi-Square test.

Results

MIH was observed in 215 (14.2%; 102 male, 113 female) children. The sample (1511 children) comprised 71 (9.9%) 8 year-olds with MIH and 144 (18.2%) 11 year-olds with MIH. A significant difference was found between 8 (9.9%) and 11-year-old (18.2%) children with MIH (p ≤ 0.001). Complications during the mother's pregnancy, birth prematurity, average breast feeding period, diarrhea frequency, digestive system diseases, asthma, frequent high fever, ear infection, renal failure, rubeola, chickenpox and parotitis were found to be significantly associated with MIH (p < 0.001).

Conclusion

There are many events that can cause MIH which we cannot control or predict. Therefore, longitudinal studies with large sample size are needed so as to determine how various likely etiological factors described affect the etiological role.

Hypomineralized Second Primary Molars as Predictor of Molar Incisor Hypomineralization

Molar incisor hypomineralization (MIH) is a developmental defect of dental enamel that shares features with hypomineralized second primary molars (HSPM). Prior to permanent tooth eruption, second primary molars could have predictive value for permanent molar and incisor hypomineralization. To assess this possible relationship, a cross-sectional study was conducted in a sample of 414 children aged 8 and 9 years from the INMA cohort in Valencia (Spain). A calibrated examiner (linear-weighted Kappa 0.83) performed the intraoral examinations at the University of Valencia between November 2013 and 2014, applying the diagnostic criteria for MIH and HSPM adopted by the European Academy of Paediatric Dentistry. 100 children (24.2%) presented MIH and 60 (14.5%) presented HSPM. Co-occurrence of the two defects was observed in 11.1% of the children examined. The positive predictive value was 76.7% (63.9–86.6) and the negative predictive value 84.7% (80.6–88.3). The positive likelihood ratio (S/1-E) was 10.3 (5.9–17.9) and the negative likelihood ratio (1-S/E) 0.57 (0.47–0.68). The odds ratio was 18.2 (9.39–35.48). It was concluded that while the presence of HSPM can be considered a predictor of MIH, indicating the need for monitoring and control, the absence of this defect in primary dentition does not rule out the appearance of MIH.

Five-minute Apgar score ≤ 5 and Molar Incisor Hypomineralisation (MIH) - a case control study

BACKGROUND

The aetiology of molar incisor hypomineralisation (MIH) is unclear. The asymmetric distribution of MIH in the dentition may indicate that an insult of short duration that affects ameloblasts at a vulnerable stage could be a causative factor. Apgar ≤ 5 at 5 min may indicate asphyxia (hypoxic-ischemic insult) during birth. It was hypnotised that low Apgar score during birth may cause MIH. The present study aimed to examine a possible association between Apgar ≤ 5 at 5 min and the occurrence of MIH.

METHOD

Two study groups were selected for examination. The cases comprised 67 children aged 8-10 years born with Apgar score equal to or below 5 after 5 min. The control group comprised 157 age-matched healthy children. First permanent molars, second primary molars and all permanent incisors were examined in all children. Clinical examination was undertaken by two calibrated examiners and intraoral close-up photographs of the teeth were later evaluated by three calibrated and blinded clinicians. Demarcated opacities, post-eruptive breakdown, atypical restorations and extractions due to MIH, according to the criteria of the European Association of Paediatric Dentistry, were assessed.

RESULTS

The prevalence of MIH did not differ between the two groups. A chi-square test failed to confirm any statistically significant relationship between 5-min Apgar scores and MIH occurrence. In addition, there was no statistically significant relationship between the number of affected first permanent molars in cases and controls.

CONCLUSION

There was no association between Apgar ≤ 5 at 5 min and the occurrence of MIH.

Treatment decisions on Molar-Incisor Hypomineralization (MIH) by Norwegian dentists - a questionnaire study

Background

The study aimed to explore the variability between the treatment decisions dentists make for MIH-affected teeth.

Methods

In 2009, a pre-coded questionnaire was sent electronically to all dentists employed by the Public Dental Service (PDS) in Norway (n = 1061). The questions were related to treatment of MIH-affected teeth, including three patient cases illustrated by photographs and written case descriptions.

Results

Replies were obtained from 61.5 % of the respondents after two reminders. In the first case, showing a newly erupted first permanent molar with moderate hypomineralization and no disintegration of the surface enamel, the preferred treatment among the majority of the respondents (53.5 %) was application of fluoride varnish, while 19.6 % would seal the fissure with GIC material. In the second case, showing a severely damaged first permanent molar in a six year old child, more than half of the respondents (57.5 %) would place a conventional glass ionomer restoration and 10.5 % would use a stainless steel crown (SSC). In the third case, showing a severely damaged permanent first molar in a nine year old child, 43.8 % of the dentists would remove only the parts with soft, damaged enamel; while 35.2 % would remove more and 21.0 % would remove all affected enamel and leave the cavity margins in sound enamel.

Conclusions

The survey shows that there is a wide disparity between clinicians’ views on how MIH affected teeth should be treated. In a severely affected first permanent molar, only a minority of dentists would remove as much tooth substance as needed to get the full benefit of the acid etch pattern in sound enamel.

On the Etiology of Molar-Incisor Hypomineralization

Molar-incisor hypomineralization (MIH) is a condition that is defined based on its peculiar clinical presentation. Reports on the etiology of the condition and possible risk factors are inconclusive and the original suggestion that MIH is an idiopathic condition is often cited. Our group was the first to suggest MIH has a genetic component that involves genetic variation in genes expressed during dental enamel formation. In this report, we provide a rationale to explain the preferential affection of molars and incisors. We suggest that MIH is a genetic condition based on its prevalence, which varies depending on the geographic location, and the evidence that on occasion second primary molars, permanent canines, and premolars can show signs of hypomineralization of enamel when molars and incisors are affected.