Pre- and postnatal determinants of deciduous molar hypomineralisation in 6-year-old children. The generation R study

Dental Developmental Defects: A Pilot Study to Examine the Prevalence and Etiology in a Population of Children between 2 and 15 Years of Age

Dental development defects (DDDs) are quantitative and/or qualitative alterations produced during odontogenesis that affect both primary and permanent dentition. The etiology remains unknown, being associated with prenatal, perinatal, and postnatal factors. The aims were to identify the possible etiological factors, as well as the prevalence of DDDs in the primary and permanent dentition in a pediatric population. Two hundred twenty-one children between 2 and 15 years of age, patients of the master's degree in Pediatric Dentistry of the Complutense University of Madrid, were reviewed. DDDs were observed in 60 children. Next, a cross-sectional, case-control study was carried out (60 children in the control group and 60 children in the case group). The parents or guardians completed a questionnaire aimed at identifying associated etiological factors. The prevalence of DDDs in patients attending our master's program in both dentitions was 27.15%. Otitis, tonsillitis, high fevers, and medication intake stood out as the most relevant postnatal factors among cases and controls. The permanent maxillary right permanent central incisor and the primary mandibular right second molar were the most affected; there were no differences in relation to gender. One out of three children who presented DDDs in the primary dentition also presented DDDs in the permanent dentition. Prenatal and postnatal etiological factors showed a significant relationship with DDD alterations, considered risk factors for DDDs in both dentitions.

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.

An Evaluation of Food and Nutrient Intake among Pregnant Women in The Netherlands: A Systematic Review

Nutritional deficiencies during pregnancy can have serious consequences for the health of the (unborn) child. This systematic review provides an updated overview of the available food and nutrient intake data for pregnant women in The Netherlands and an evaluation based on the current recommendations. Embase, MEDLINE, and national institute databases were used. Articles were selected if they had been published since 2008 and contained data on food consumption, nutrient intake, or the status of healthy pregnant women. A qualitative comparison was made with the 2021 Dutch Health Council recommendations and reference values. A total of 218 reports were included, representing 54 individual studies. Dietary assessments were primarily performed via food frequency questionnaires. Protein, vitamin A, thiamin, riboflavin, vitamin B₆, folate, vitamin B₁₂, vitamin C, iron, calcium, and magnesium intakes seemed to be adequate. For folate and vitamin D, supplements were needed to reach the recommended intake. The reasons for concern are the low intakes of fruits, vegetables, and (fatty) fish, and the intakes of alcohol, sugary drinks, and salt. For several foods and nutrients, no or limited intake data were found. High-quality, representative, and recent data are needed to evaluate the nutrient intake of pregnant women in order to make accurate assessments and evaluations, supporting scientific-based advice and national nutritional policies.

Oral and craniofacial research in the Generation R study: an executive summary

OBJECTIVES

Oral conditions are of high prevalence and chronic character within the general population. Identifying the risk factors and determinants of oral disease is important, not only to reduce the burden of oral diseases, but also to improve (equal access to) oral health care systems, and to develop effective oral health promotion programs. Longitudinal population-based (birth-)cohort studies are very suitable to study risk factors on common oral diseases and have the potential to emphasize the importance of a healthy start for oral health. In this paper, we provide an overview of the comprehensive oral and craniofacial dataset that has been collected in the Generation R study: a population-based prospective birth cohort in the Netherlands that was designed to identify causes of health from fetal life until adulthood.

METHODS

Within the multidisciplinary context of the Generation R study, oral and craniofacial data has been collected from the age of 3 years onwards, and continued at the age of six, nine, and thirteen. Data collection is continuing in 17-year-old participants.

RESEARCH OUTCOMES

In total, the cohort population comprised 9749 children at birth, and 7405 eligible participants at the age of seventeen. Based on questionnaires, the dataset contains information on oral hygiene, dental visits, oral habits, oral health-related quality of life, orthodontic treatment, and obstructive sleep apnea. Based on direct measurements, the dataset contains information on dental caries, developmental defects of enamel, objective orthodontic treatment need, dental development, craniofacial characteristics, mandibular cortical thickness, and 3D facial measurements.

CONCLUSIONS

Several research lines have been set up using the oral and craniofacial data linked with the extensive data collection that exists within the Generation R study.

CLINICAL RELEVANCE

Being embedded in a multidisciplinary and longitudinal birth cohort study allows researchers to study several determinants of oral and craniofacial health, and to provide answers and insight into unknown etiologies and oral health problems in the general population.

The Prevalence of Developmental Enamel Defects in Israeli Children and Its Association with Perinatal Conditions: A Cross-Sectional Study

Molar incisor hypomineralization (MIH) and deciduous molar hypomineralization (DMH) affect the first permanent molars and second primary molars, respectively, causing a greater dental treatment burden and worse oral health quality of life among affected children. We assessed the prevalence and risk factors of MIH and DMH among 1209 children aged 3-13 years who attended a university dental clinic in Israel in 2019-2020. Clinical examinations were conducted to assess the presence of DMH and MIH. Potential etiological factors of MIH and DMH, including demographics, the mother's perinatal health, and the child's medical history during the first three years of life, were retrieved using a questionnaire. To examine the associations between the demographic and clinical variables and the prevalence of MIH and DMH, continuous variables were tested using the Kruskal-Wallis test with Bonferroni corrections. Categorical variables were analyzed by chi-squared test. Multivariate logistic regression was conducted to evaluate which of the significant variables found in the univariate analysis could predict a diagnosis of both MIH and DMH. The prevalence of MIH and DMH was 10.3% and 6.0%, respectively. Age ≥ 5 years, taking medications during pregnancy and severe lesions were associated with a greater risk for a diagnosis of DMH + MIH. Multivariate logistic regression with adjustment for age showed that the severity of hypomineralization was positively and significantly associated with a diagnosis of MIH + DMH with an odds ratio of 4.18 (95% confidence interval 1.26-17.16), p = 0.03. MIH should be diagnosed and monitored in young children to prevent further deterioration. Moreover, a preventive and restorative program for MIH should be established.

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.

Lückenschluss nach Extraktion von Sechsjahrmolaren mit Molaren-Inzisiven-Hypomineralisation unterstützt durch das myofunktionell-kieferorthopädische Therapiekonzept „mykie“ – Ein Fallbericht

Die Molaren-Inzisiven-Hypomineralisation (MIH) stellt den behandelnden Zahnarzt und Kieferorthopäden vor schwierige Therapieentscheidungen. Einerseits stellt der Zahnerhalt die höchste Priorität dar, ist aber bei einer großflächigen Zerstörung des Zahnes, oft begleitet mit ausgeprägten Hypersensitivitäten, nicht immer zu gewährleisten. Der vorliegende Patientenfall skizziert einen Therapieansatz, bei dem die vier Sechsjahrmolaren aufgrund von MIH sehr frühzeitig im Alter von 8,9 Jahren extrahiert wurden. Der hier durchgeführte Lückenschluss wurde mit dem kombiniert myofunktionell-kieferorthopädischen Behandlungskonzept mykie (= myofunktionelle Kieferorthopädie) unterstützt.

Space Closure After Extraction of Permanent First Molars with molar incisor hypomineralization Supported by the Myofunctional-Orthodontic Therapy Concept mykie – A Case Report

Etiology Study of Acquired Developmental Defects of Enamel and Their Association with Dental Caries in Children between 3 and 19 Years Old from Dolj County, Romania

Background: Developmental defects of enamel (DDE) are frequently encountered in primary and permanent teeth, yet their etiology is not completely known. Enamel hypoplasia is considered a predisposing factor for early caries. The objective of this study was the evaluation of several risk factors potentially causing DDE and the possible association between DDE and dental caries. Methods: This study was performed on a group of 213 rural children from Romania. It combined a thorough dental examination for all children, and a questionnaire filled in by their mothers, regarding the evolution of their pregnancy and the child’s health status in the first years of life. Results: There was no statistically significant association between DDE presence and data regarding the evolution of pregnancy, mothers’ health status or children’s conditions during early childhood. There was a significant association between the use of amoxicillin, ibuprofen, and cephalosporin during the period of formation of permanent teeth, and one environmental factor (water source), and the presence of DDE (Chi Square, p < 0.05). Also, DDEs were associated with the presence of caries (Fisher, p = 0.001). Conclusions: Children who consumed water from private wells and children who received medication during early childhood developed more enamel defects, presenting a higher risk of caries development.

Vitamin D status and tooth enamel hypomineralization are not associated in 4-y-old children: An Odense Child Cohort study

Early fetal stages of tooth development are vitamin D-dependent, suggesting an impact of vitamin D status in pregnancy on tooth mineralization in human populations. We examined the association between pregnancy and cord serum 25-hydroxyvitamin D (s-25(OH)D) and hypomineralization of the second primary molars (HSPM) in the 4-year-old children in the prospective, population-based Odense Child Cohort, Denmark. S-25(OH)D was measured in early pregnancy (<20 weeks, n = 753); late pregnancy (≥20 weeks, n = 841); and in umbilical cord blood (n = 1,241) using liquid chromatography-tandem mass spectrometry. HSPM was scored using modified European Academy of Paediatric Dentistry judgment criteria. The median [Q1;Q3] s-25(OH)D was 65.0 [49.4;78.0], 79.2 [60.4;95.8], and 45.1 [31.2;60.5] nmol/L in early pregnancy, late pregnancy, and cord blood, respectively. The prevalence of HSPM was 54.7%; creamy/white demarcated opacities 79.5%; yellowish/brownish demarcated opacities 14.9%; post-eruptive breakdown 5.2%; atypical restoration 0.4%. No univariate or adjusted associations with HSPM were detected for pregnancy or cord s-25(OH)D as a continuous variable or categorized into quartiles or routine clinical cut-offs, or when classifying HSPM by severity. In exploratory multiple regression analysis, HSPM was inversely associated with the length of gestation, adjusted odds ratio (aOR) 0.82 (95% C.I 0.74-0.92, p < 0.001), and directly associated with maternal education, aOR 1.57 (95% C.I 1.18-2.08, p = 0.002). In a population with relatively high s-25(OH)D concentrations and generally healthy mothers and children, pregnancy and cord blood vitamin D status was not associated with HSPM. The associations between HSPM and shorter gestational length and higher maternal education warrant further study.

Impact of hypomineralised second primary molar on preschoolers' oral health-related quality of life-A hierarchical approach

BACKGROUND

Hypomineralised second primary molar (HSPM) is a developmental enamel defect associated with dental caries.

AIM

To evaluate the impact of HSPM on oral health-related quality of life (OHRQoL) in preschoolers through hierarchical analysis.

DESIGN

This population-based cross-sectional study assessed 834 5-year-old preschoolers, in Teresina, Piauí, Brazil, using sociodemographic questionnaires and Early Childhood Oral Health Impact Scale (ECOHIS). Dental examination was performed by two calibrated examiners (κ ≥ 0.80) for the diagnosis of HSPM (EAPD), dental caries (dmft and pufa indices), and malocclusion (Foster and Hamilton criteria). Analysis of the determinants of OHRQoL was stratified at three levels (P < .05).

RESULTS

Severe HSPM was associated with OHRQoL in bivariate analysis (P < .05). In adjusted final multivariate analysis (model 1), the presence of dental caries with or without clinical consequences was associated with worse OHRQoL (P < .05). In model 2, after the removal of dental caries, preschoolers with severe HSPM had greater probability of having a negative impact on OHRQoL in the child impact section (RR = 2.14; 95% CI = 1.26-3.65), family impact section (RR = 1.99; 95% CI = 1.16-3.42), and total score (RR = 2.09; 95% CI = 1.25-3.49) of the ECOHIS.

CONCLUSION

Severe HSPM had a negative impact on the OHRQoL of preschoolers and their families, but the presence of dental caries neutralised this impact.

Factors and Mechanisms Involved in Acquired Developmental Defects of Enamel: A Scoping Review

BACKGROUND

Developmental Defects of Enamel (DDE) is a pathology of the teeth that can greatly alter the quality of life of patients (hypersensitivity, esthetic issues, loss of function, etc.). The acquired DDE may occur as a result of a wide range of acquired etiological factors and his prevalence of this pathology may reach up to 89.9%. The main objective of this research was to identify and analyze, in current literature, the factors related to acquired DDE, in order to propose a general theory about the mechanisms involved.

METHODS

The search of the primary literature was conducted until [December 31, 2021]. Our search strategy uses the Pubmed/MEDLINE database and was structured around 3 terms ["Development," "Defect," and "Enamel"]. To be included, references had to be primary studies, written in English. Exclusion criteria were reviews, in vitro, animal, genetic or archeology studies, and studies focused on clinical management of DDE. One hundred and twenty three articles were included in this scoping review: 4 Randomized clinical trials, 1 letter, 5 cases reports, 2 fundamentals studies, and 111 observational studies (33 Cross-sectional studies, 68 Cohort study and 10 Case-control study). The quality of evidence was assessed using the PEDro scale for clinical trials, the Newcastle-Ottawa scale for observational studies, and a published tool to assess the quality of case reports and case series.

RESULTS

A scoping review of the literature identified 114 factors potentially involved in acquired DDE. The most frequently encountered pathologies are those causing a disorder of calcium homeostasis or a perturbation of the ARNT pathway in mother or child. The link between the ARNT pathway and metabolism deficiency in uncertain and needs to be defined. Also, the implication of this mechanism in tissue impairment is still unclear and needs to be explored.

CONCLUSIONS

By identifying and grouping the risk factors cited in the literature, this taxonomy and the hypotheses related to the mechanism allow health practitioners to adopt behaviors that limit the risk of developing aDDE and to set up a prevention of dental pathology. In addition, by reviewing the current literature, this work provides guidance for basic research, clinical studies, and literature searches.

DNA methylation in childhood dental caries and hypomineralization

OBJECTIVES

Epigenetic modulation of gene expression may be important in dental conditions, including dental caries and enamel hypomineralisation. The aims of this study were to assess associations between DNA methylation in cord blood leucocytes at birth, and caries experience and enamel hypomineralisation at six years of age.

METHOD

The study sample was from a birth cohort study of twins. Dental examinations at six years identified the presence/absence of (i) 'any caries' (untreated and treated caries), (ii) 'advanced caries' (untreated, advanced caries and/or past treatment) and (iii) hypomineralised second primary molars (HSPM). Genome-wide analysis of DNA methylation was performed on cord blood of 27 twin pairs (14 dizygotic and 13 monozygotic) using the Illumina Infinium MethylationEPIC BeadChip array. Differentially methylated CpGs (DMCpGs) and regions (DMRs) associated with each dental outcome were investigated, while accounting for the relatedness of twins. Results with a false discovery rate <0.05 were treated as statistically significant.

RESULTS

19 children had 'any caries', 15 had 'advanced' caries, and 18 had HSPM. No DMCpGs were associated with 'any caries', 16 and 19 DMCpGs were associated with 'advanced caries' and HSPM, respectively. DMRs were identified in association with all three outcomes. Genes implicated by these analyses included PBX1, ACAT2, LTBP3 and DDR1 which have been linked with dental tissue development in genetic studies.

CONCLUSION

This exploratory study identified differential methylation in several genes at birth associated with dental caries and HSPM at six years. Further research may provide valuable insights into aetiology of dental disease and/or reveal novel molecular-based approaches for early risk stratification.

CLINICAL SIGNIFICANCE

Epigenetic differences at birth are likely to be associated with dental health at six years and may be valuable biomarkers of early influences on dental health.

Prenatal, perinatal and postnatal events associated with hypomineralized second primary molar: a systematic review with meta-analysis

OBJECTIVE

The etiology of hypomineralized second primary molar (HSPM) appears to be multifactorial but remains uncertain. Thus, the objective was to systematically review studies that investigated adverse health conditions in the prenatal, perinatal and postnatal periods associated with HSPM.

MATERIAL AND METHODS

The search was carried out in five databases and in gray literature. The risk of bias of observational studies was analyzed according to the Newcastle-Ottawa scale.

RESULTS

A total of 1878 studies were identified. Fourteen were eligible, and seven were included in the meta-analysis. Maternal smoking (OR = 2.88; 95%CI: 1.62-5.15) and presence of maternal hypertension (OR = 2.91; 95%CI: 1.35-6.28) were significantly associated with higher odds of HSPM. In the perinatal period, factors associated with HSPM were low birth weight (OR = 1.50; 95%CI: 1.15-1.96), prematurity (OR = 1.93; 95%CI: 1.37-2.71), delivery complications (OR = 2.42; 95%CI: 1.52-3.83) and need for an incubator (OR = 1.65; 95%CI: 1.01-2.70). Not breastfeeding (OR = 1.26; 95%CI: 1.01-1.58), use of antibiotics by the child (OR = 1.24; 95%CI: 1.04-1.48), fever (OR = 1.37; 95%CI: 1.10-1.72) and asthma (OR = 1.91; 95%CI: 1.16-3.13) were the postnatal factors associated with HSPM.

CONCLUSION

Maternal smoking, maternal hypertension, low birth weight, prematurity, delivery complications, need for incubation, not breastfeeding, antibiotic use, fever and childhood asthma were associated with HSPM. Well-designed prospective cohort studies are needed. Clinical relevance Understanding the etiological factors can be guiding aspects for individual clinical approaches, as well as guiding the design of preventive interventions for HSPM.

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.

Caries experience among children born after a complicated pregnancy

Objectives

Behavioural and lifestyle factors, as oral hygiene and diet, are well‐established risk factors in the pathogenesis of dental caries, though displaying large differences in susceptibility across individuals. Since enamel formation already starts in utero, pregnancy course and outcome may eventually play a role in enamel strength and caries susceptibility. Therefore, we studied the association between history of pregnancy complications and the caries experience in their six‐year‐old children. The pregnancy complications included small for gestational age (SGA), spontaneous preterm birth (sPTB), gestational hypertension (GH), pre‐eclampsia (PE), individually, and a combination of those, designated as placental syndrome.

Methods

This study was embedded in Generation R, a prospective longitudinal Dutch multiethnic pregnancy cohort study. Information about pregnancy complications was obtained from questionnaires completed by midwives and obstetricians with cross‐validation in medical records. These included SGA, sPTB, GH and PE. Caries experience was assessed with the decayed, missing and filled teeth (dmft) index at a mean age of six years. The association between dental caries experience and a history of pregnancy complications was studied by using hurdle negative binomial (HNB) models.

Results

We were able to assess the dmft index in 5323 six‐year‐old children (mean age 6.2 years, SD 0.5). We did not find an association between the different pregnancy complications and dental caries experience in childhood, whether for SGA, sPTB, GH, PE, or for the combined outcome placental syndrome (HNB estimates: OR 1.02, 95%CI 0.87 ‐ 1.19; RR 0.90, 95%CI 0.78 ‐ 1.04). Further adjustment of the models with different confounders did not alter the outcome.

Conclusions

Although it is expected that prenatal stress can be a risk factor for caries development later in life, our findings do not support this hypothesis. Therefore, we believe disparities in caries experience between children are probably not explained by early life events during a critical intrauterine period of development.

Pre-term birth and asthma is associated with hypomineralized second primary molars in pre-schoolers: A population-based study

BACKGROUND

Hypomineralized second primary molar (HSPM) is a developmental enamel defect that represents a caries-risk factor. There are few studies about HSPM epidemiology in representative populations.

AIM

To determine the prevalence and factors associated with HSPM in pre-schoolers.

DESIGN

This is a cross-sectional population-based study of 5-year-old pre-schoolers from Teresina, Brazil. The sample was randomly selected and stratified by geographic region of the city, type of school (public and private), and sex of the pre-schoolers (n = 811). Sociodemographic status and pre-, peri-, and post-natal conditions were collected by structured questionnaires. Two calibrated examiners diagnosed HSPM using the criteria of the European Academy of Paediatric Dentistry for molar-incisor hypomineralization. Severity, colour, location, and extent of lesions were also evaluated. Descriptive analysis of the data and a Poisson regression analysis were performed (P < .05).

RESULTS

The prevalence of HSPM was 14.9. Demarcated opacities (75.6%) and white/cream colour were the most prevalent (71.4%). Pre-term pre-schoolers had 66% (PR = 1.66, 95% CI = 1.07-2.58), and those who reported asthma in the first year of life had 69% (PR = 1.69, 95% CI = 1.01-2.85) higher prevalence of HSPM.

CONCLUSIONS

Pre-term birth and reported asthma in the first year of life were associated with HSPM. The prevalence of HSPM in pre-schoolers aged 5 years old in Teresina was high.

Relationship between deciduous molar hypomineralisation and parameters of bone metabolism in preschool children

BACKGROUND

The aetiology of deciduous molar hypomineralisation (DMH) is still largely unknown.

AIM

The aim of the study was to elucidate the occurrence of DMH as a function of the parameters of bone metabolism, as it is suspected that abnormalities in these parameters may affect the mineralisation of teeth.

DESIGN

In a prospective cohort study, 958 children aged 1-6 years were examined. The inclusion criteria were: a blood sample to determine the parameters of bone metabolism; and documentation of enamel mineralisation using the European Academy of Paediatric Dentistry (EAPD) criteria. Multivariable methods were applied to analyse the incidence of DMH relative to the concentrations of serum calcium, phosphate, vitamin D, vitamin B12 and alkaline phosphatase, taking into account the effects of age, gender and height.

RESULTS

The proportion of children diagnosed with DMH was 4.0% (38 of 958). A significant difference between DMH-affected and non-DMH-affected children was found only in the serum concentration of calcium (2.47 ± 0.08 mmol/l vs. 2.52 ± 0.10 mmol/l, respectively, P = 0.004). The risk of DMH significantly increased, by 1.63-fold (95% CI: 1.03-2.57), if the calcium level dropped by 0.1 mmol/l, regardless of age, gender or adjusted height. During the follow-up examination of 17 DMH-affected subjects, the calcium level remained consistently low 1 year later (t-test, P > 0.05).

CONCLUSION

Children with DMH showed consistently subclinically lower serum calcium levels. No associations were found for other parameters.

Second primary molar hypomineralisation and drugs used during pregnancy and infancy. A systematic review

OBJECTIVES

Hypomineralised second primary molars (HSPM) are due to idiopathic hypomineralisation that affects from 1- to 4-s primary molars, and its aetiology remains unclear. Our objective was to systematically review studies in which the investigators had studied the association between HSPM and drug use during pregnancy and the first year of life.

MATERIALS AND METHODS

A systematic search for publications until July 2018 was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. No restrictions were placed on year of publication. The PECO Question was as follows: P, children exposed to drugs during pregnancy and the first year of life; E, drugs to which mothers, during pregnancy and their offspring were exposed; C, control groups from studies with the same characteristics not exposed to drugs during pregnancy and the first year of life; and O, relationship between drug exposure during pregnancy and the first year of life and HSPM. Two reviewers extracted the data and assessed the risk of bias using the Newcastle-Ottawa Scale criteria.

RESULTS

We initially identified 986 articles, or which seven were selected for review: two case-control studies, one cross-sectional studies and four cohort studies. Four studies reported data on drug consumption during pregnancy and four investigated drug use during the first year of life and the occurrence of enamel defects in primary dentition.

CONCLUSIONS

There is no clear evidence that the use of drugs during pregnancy and during the first year of life is associated with HSPM. Further well-designed prospective studies are needed.

CLINICAL RELEVANCE

Determining the etiological factors related to the development of HSPM would help to establish preventive protocols in patients at potential risk. As HSPM is predictive of molar incisor hypomineralisation (MIH), the application of preventive protocols would avoid complications in both the primary and permanent dentition.

A systematic review and meta-analysis of systemic exposure associated with molar incisor hypomineralization

OBJECTIVE

To evaluate systemic exposures associated with molar incisor hypomineralization (MIH).

METHODS

This systematic review was performed using published observational studies that evaluated the systemic exposures associated with MIH. The sources of articles searched were PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library and Grey literature. The risk of bias was analysed according to the Newcastle-Ottawa Scale for quality assessment. The meta-analysis was performed considering the exposures during the prenatal, perinatal and postnatal periods using the CMA software.

RESULTS

A total of 4207 articles were identified. Twenty-nine studies were eligible for inclusion and 27 were included in the meta-analysis. The studies presented low and moderate risks of bias, except for one that was classified as having a high risk of bias. Maternal illness during pregnancy (OR 1.40; 95% CI 1.18-1.65, P < 0.0001) and psychological stress (OR = 2.65; 95% CI 1.52-4.63; P = 0.001) was observed to be significantly associated with higher odds of MIH. During the perinatal period, caesarean delivery (OR = 1.32, 95% CI 1.11-1.57, P = 0.001) and delivery complications (OR = 2.06; 95% CI 1.47-2.88, P < 0.0001) were also associated with MIH. In the postnatal period, only respiratory diseases (OR = 1.98; 95% CI 1.45-2.70, P < 0.0001) and fever (OR = 1.50; 95% CI 1.22-1.84; P < 0.0001) were associated with higher prevalence of MIH. The evidence was graded as very low quality.

CONCLUSIONS

Maternal illness, psychological stress, caesarean delivery, delivery complications, respiratory diseases and fever during the first years of a child's life were significantly associated with a higher odds of MIH. However, this should be interpreted with caution, once the primary studies were observational, with serious limitations according to the risk of bias, imprecision, and inconsistency. Further, well-designed cohort studies are still required.

Prevalence, defect characteristics and distribution of other phenotypes in 3- to 6-year-old children affected with Hypomineralised Second Primary Molars

PURPOSE

To assess the prevalence, severity and defect characteristics of hypomineralised second primary molars in schoolgoing children along with distribution of other phenotypes.

METHODS

A total of 3013, 3- to 6-year-old children were examined for the presence of hypomineralised second primary molars (HSPMs) using an adapted version of EAPD Criteria (2003). The molars were evaluated for the presence, location and colour of demarcated opacities along with associated post-eruptive breakdown (PEB) and atypical restorations. A thorough examination of the entire dentition was followed for evaluation of teeth other than primary second molars for the presence of similar hypomineralised defects. Data were analysed using Chi Square, Fisher exact's and Mann-Whitney U tests at α = 0.05.

RESULTS

A total of 3013 out of 3200 children were included having a mean age of 4.25 ± 0.5 years and deft of 2.1 ± 0.5. Using the adapted version of EAPD 2003 criteria for MIH, the children were evaluated for the presence of hypomineralised second primary molars, the prevalence of which was found to be 7.9%. Hypomineralisation defects were more commonly observed in the maxillary arch (53.4% vs. 42.8%, p = 0.04) with creamish white opacities involving the buccal and lingual surfaces being the most common defects (43.6%). The mean number of HSPMs per child was 1.9. Other phenotypes included demarcated opacities majorly on primary canines (6.6%) followed by primary first molars (4.6%).

CONCLUSIONS

Hypomineralised primary second molars are a fairly common condition affecting approximately 7.9% of the population thus warranting early recognition and management.

Food Consumption, Nutrient Intake and Status during the First 1000 days of Life in the Netherlands: a Systematic Review

Adequate nutrition is essential for growth and development in early life. Nutritional data serves as a basis for national nutritional guidelines and policies. Currently, there is no insight into the availability of such data during the first 1000 days of life. Therefore, a systematic review was performed, following the PRISMA reporting guideline, to identify studies on food consumption, nutrient intake or status in the Netherlands. Potential gaps were identified, and the quality of the studies is discussed. The databases Embase and Medline were used, as well as databases from national institutes. Articles published in 2008-2018 were screened by two independent reviewers. In total 601 articles were identified, of which 173 were included. For pregnant women, 32 studies were available with nutritional data, for young children 40 studies were identified. No studies were available for breastfeeding women. A large variety of foods and nutrients were assessed, however certain nutrients were lacking (e.g., vitamin K). Overall, the studies had methodological limitations, making the data unsuitable to assess nutrient inadequacies. There is a need for recent, high quality nutritional research to strengthen the understanding of the nutritional needs and deficiencies during early life, and is fundamental for national guidelines and policies.

Developmental defects of enamel in primary teeth: highly prevalent, unevenly distributed in the oral cavity and not associated with birth weight

AIM

Estimate the prevalence of developmental defects of enamel (DDE) in the primary dentition, describe the distribution among tooth groups and investigate the association with birth weight.

METHODS

A cross-sectional study was conducted with a sample of 827 children aged 2-5 years representative of the city of Canela in southern Brazil. Demographic characteristics (gender and age) and birth weight were collected from vaccination cards. The diagnosis of DDE was performed by six trained examiners following the criteria of the Federation Dentaire International. DDE were described both jointly and separately as opacity and hypoplasia. Statistical analysis involved the Chi square test, Mann-Whitney test and Poisson regression with robust variance.

RESULTS

The prevalence of DDE was 55.1% (95% CI 51.6-58.5%), with a mean of 3.0 ± 2.2 teeth affected. Opacity was the more frequent defect (50.4%), followed by hypoplasia (15.5%). Distribution of the defects was uneven, with opacity predominant on second molars and hypoplasia predominant on canines and second molars. Children with a low birth weight did not have a greater probability of opacity (PR: 1.13; 95% CI 0.91-1.41), hypoplasia (PR: 1.33; 95% CI 0.80-2.22) or DDE (PR: 1.11; 95% CI 0.91-1.37).

CONCLUSION

The prevalence of DDE was high, predominant on second molars and not associated with birth weight. These findings indicate directions for future examination/diagnosis protocols and specific orientations.

Etiology of Hypomineralized Second Primary Molars: A Prospective Twin Study

The etiology of hypomineralized second primary molars (HSPM) is unclear, but genetic and environmental factors have been proposed. The aim of this study was to investigate the relative contribution of genes and environment to the etiology of HSPM and to identify potential environmental risk factors in a longitudinal twin cohort. Children from twin pregnancies ( N = 250) were recruited antenatally, and detailed demographic, health, and phenotypic data were collected at recruitment, 24- and 36-wk gestation, birth, and 18 mo of age. 25-Hydroxyvitamin D was quantified for mothers at 28-wk gestation and infants at birth. Dental examinations were conducted on the twins at 6 y of age to determine the presence, severity, and extent of HSPM per standardized criteria. To investigate associations of environmental risk factors with HSPM, multiple logistic regression models were fitted with generalized estimating equations to adjust for twin correlation. Within- and between-pair analyses were performed for unshared continuous variables: birthweight and birth 25-hydroxyvitamin D. Twin-twin concordance for monozygotic (MZ) and dizygotic (DZ) pairs was calculated and compared after adjusting for identified risk factors. A total of 344 twins underwent the 6-y-old dental assessment; HSPM occurred in 68 (19.8%). After adjusting for potential confounders, vitamin D levels at birth, infantile eczema, dizygosity, in vitro fertilization, socioeconomic position, and maternal smoking beyond the first trimester of pregnancy demonstrated the strongest associations with HSPM. Overall concordance for HSPM was 0.47 (95% CI, 0.32 to 0.62) with weak evidence ( P = 0.078) of higher concordance in MZ twins (0.63; 95% CI, 0.38 to 0.89) as compared with DZ twins (0.41; 95% CI, 0.24 to 0.58). After adjusting for known risk factors, there was no evidence ( P = 0.172) for an additive genetic influence. These findings suggest that shared and unshared environmental factors, such as maternal smoking later in pregnancy and infantile eczema, are important in the etiology of HSPM.

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.

Preliminary investigation of the variations in root canal morphology of hypomineralised second primary molars

AIM

To investigate the root canal morphology of hypomineralised second primary molars(HSPM) using micro-CT(μCT) compared with non-hypomineralised second primary molars (non-HSPM).

METHODOLOGY

Ten HSPM and 10 non-HSPM were divided into Group 1(maxillary HSPM), Group 2 (mandibular HSPM), Group 3(maxillary non-HSPM), and Group 4 (mandibular non-HSPM). All teeth were scanned using μCT to assess the following parameters: (i) root canal configuration, (ii) pulp volumes, and (iii) the influence of the root canal system landmarks on access cavity outline forms and canal curvature. Two-way ANOVA was employed for descriptive analysis (P < 0.05).

RESULTS

At the furcation level, there was minimal variation in the number of canals. In the mesiobuccal root, Group 1 showed higher frequency of multiple canals in the middle (85.7%) and apical (85.7%) thirds compared with Group 3. In the mesial root, Group 4 demonstrated multiple canals at the furcation (60%) compared with Group 2(33.3%). In the distal root, Group 2 demonstrated a higher percentage of multiple canals at the apical level (100%) compared with Group 4. The mean pulp volumes of Group 2 and Group 4 were 54.1 mm³ (16.7) and 30 mm³ (5.12), respectively, which was statistically significant (P < 0.05). The canal curvature values did not differ significantly between HSPM and non-HSPM groups.

CONCLUSIONS

HSPM exhibited greater variations in their root canal configuration when compared to non-HSPM.

Foetal, neonatal and child vitamin D status and enamel hypomineralization

Objectives

Recent literature suggested that higher vitamin D concentrations in childhood are associated with a lower prevalence of molar incisor hypomineralization (MIH). As tooth development already starts in utero, we aimed to study whether vitamin D status during foetal, postnatal and childhood periods is associated with the presence of hypomineralized second primary molars (HSPMs) and/or MIH at the age of six.

Methods

Our study was embedded in the Generation R Study, a population‐based, prospective cohort from foetal life onwards in Rotterdam, the Netherlands. HSPMs and MIH were scored from intraoral photographs of the children at their age of six. Serum 25(OH)D concentrations were measured at three points in time, which resulted in three different samples; mid‐gestational in mothers’ blood (n = 4750), in umbilical cord blood (n = 3406) and in children's blood at the age of 6 years (n = 3983).

Results

The children had a mean (±SD) age of 6.2 (±0.5) years at the moment of taking the intraoral photographs. After adjustment for confounders, no association was found between foetal 25(OH)D concentrations and the presence of HSPMs (OR 1.02 per 10 nmol/L higher 25(OH)D, 95% CI: 0.98‐1.07) or MIH (OR 1.05 per 10 nmol/L increase, 95% CI: 0.98‐1.12) in 6‐year‐olds. A higher 25(OH)D concentration in umbilical cord blood resulted in neither lower odds of having HSPM (OR 1.05, 95% CI: 0.98‐1.13) nor lower odds of having MIH (OR 0.95, 95% CI: 0.84‐1.07) by the age of six. Finally, we did not find higher 25(OH)D concentrations at the age of six to be associated with a significant change in the odds of having HSPM (OR 0.97, 95% CI: 0.92‐1.02) or MIH (OR 1.07, 95% CI: 0.98‐1.16).

Conclusions

25(OH)D concentrations in prenatal, early postnatal and later postnatal life are not associated with the presence of HPSMs or with MIH at the age of six. Future observational research is required to replicate our findings. Furthermore, it is encouraged to focus on identifying other modifiable risk factors, because prevention of hypomineralization is possible only if the causes are known.

Dental Caries and Developmental Defects of Enamel in the Primary Dentition of Preterm Infants: Case-Control Observational Study

AIM

Assessment of dental health in the primary dentition of preterm infants (PTI) including investigation of mother- and infant-related risk factors in a case-control study design.

MATERIAL AND METHODS

One hundred twenty-eight infants aged 3-4 years were included. Sixty-four PTI (27 males) were randomly selected from the preterm registry of the Jena University Hospital. As a control group served 64 full-term infants (FTI) recruited from the Department of Paediatric Dentistry, matched for age and sex. Dental examinations were provided by one dentist under standard clinical conditions. Caries was scored using the International Caries Detection and Assessment System (ICDAS II) and the DMFT, gingival health using the Periodontal Screening Index, and developmental defects of enamel using the DDE index. Mother- and infant-related factors were collected via a questionnaire and from medical records.

RESULTS

The caries prevalence was 50.0% (ICDAS II >0) in PTI and 12.5% (ICDAS II >0) in FTI. The caries experience was higher in PTI (DMFT 1.0 ± 3.1) than in FTI (DMFT 0.3 ± 1.0). PTI had a higher risk of caries (OR 7.0), initial lesions (OR 6.2), DDE (OR 7.5), and gingivitis (OR 6.5) than FTI. The highest risk occurred in PTI with an extremely low birth weight (<1,000 g). A higher risk of DDE was present when mothers suffered from illness during pregnancy (OR 3.9). A higher risk of caries was revealed in infants with respiratory syndrome (OR 6.2) or when their mothers had a lower socioeconomic status (OR 6.3).

CONCLUSIONS

PTI had less healthy teeth than FTI and are at a higher risk for DDE, caries, and gingivitis. The poorer dental health in PTI is associated with a low birth weight, a low socioeconomic status, and mothers' illness during pregnancy.

Generation R birth cohort study shows that specific enamel defects were not associated with elevated serum transglutaminase type 2 antibodies

AIM

Coeliac disease can induce specific enamel defects (SED), but little is known about the consequences of antitissue transglutaminase (TG2A) autoimmunity. We investigated whether TG2A positivity in children and their mothers was associated with SED in the primary dentition.

METHODS

Maternal and child serum immunoglobulin A-TG2A levels were measured as part of the Generation R prospective cohort study. Clinical oral photographs of the primary dentition were taken, and SED and caries were recorded. We performed logistic regression analysis.

RESULTS

We analysed data on 4775 mothers and 4233 children (median age of 6.2 ± 0.5 years). SED and caries were not associated with maternal TG2A levels. The 59 TG2A-positive children tended to have more SED, particularly the 31 in the strongly positive subgroup, with odds ratio of 1.72 and 2.29, respectively. A positive linear trend was observed between higher TG2A levels and paediatric SED (p = 0.04), but this became nonsignificant after adjusting for ethnic and socio-economic background. No difference in caries was found between the groups.

CONCLUSION

TG2A did not play an independent role on SED in the primary dentition during pregnancy and childhood, and the relationship may be explained by ethnic and socio-economic background.

Developmental defects of enamel in primary teeth - findings of a regional German birth cohort study

Background

The aim was to assess the prevalence, distribution and associated risk factors of developmental defects of enamel (DDE) in 3-year-old Thuringian children in 2013 as part of a prospective cohort study.

Methods

The subjects (n = 377) were all participants in a Thuringian oral health programme. Children of the birth cohort 2009/2010 were invited to dental examination in the first year of life, followed up with continuous dental care over the next 3 years. Dental caries was scored using the WHO diagnostic criteria expanded to the d1-level without radiography. Enamel defects were assessed according to the modified DDE Index. Data were analysed statistically (multivariate logistic regression).

Results

The children were aged 3.3 ± 0.7 years and 52.5 % of them were male. Caries prevalence was 15.6 % and caries experience 0.9 ± 3.3 d_1-4mfs. The prevalence of DDE was 5.3 % with an average of 2.7 (±1.4) affected teeth. Second primary molars were the most affected teeth and demarcated opacities the most prevalent type. No child had Amelogenesis imperfecta and six children showed hypomineralised second primary molars. Enamel defects were associated with preterm birth (p = 0.024; OR = 4.9) and hospitalisation in the first year of life (p = 0.013; OR = 4.6).

Conclusion

A relatively small proportion of 3-year-old Thuringian children suffered from DDE, with second primary molars as the most affected teeth and demarcated opacities as the most prevalent type of defect. Preterm birth and hospitalisation in first year of life can be considered as risk factors for DDE in the primary dentition.

Trial Registration

German Clinical Trials Register, DRKS00003438

Etiology of molar incisor hypomineralization - A systematic review

OBJECTIVES

Molar incisor hypomineralization (MIH) is a common developmental dental defect of permanent teeth, which can increase the risk of dental caries, infection and hospitalization. The etiology is currently unclear although prenatal or early childhood health factors are suspected. The aim of this systematic review was to assess the strength of evidence linking etiological factors with MIH.

METHODS

A systematic search was conducted using the Medline and Embase electronic databases for studies investigating environmental etiological factors of MIH. Two reviewers assessed the eligibility of studies. The level of evidence and bias was determined for all eligible studies according to Australian National Health and Medical Research Council guidelines for systematic reviews of etiology and the Newcastle-Ottawa Scale.

RESULTS

From a total of 2254 studies identified through electronic and hand searching, 28 were eligible for inclusion. Twenty-five of these investigated MIH and three investigated a related condition in primary teeth, hypomineralized second primary molars (HSPM), and these were analysed separately. A limited number of studies reported significant associations between MIH and pre- and perinatal factors such as maternal illness and medication use in pregnancy, prematurity and birth complications. Early childhood illness was implicated as an etiological factor in MIH in several studies, in particular fever, asthma and pneumonia. The studies investigating HSPM revealed an association with maternal alcohol consumption, infantile fever and ethnicity. However, the validity of these findings is impaired by study design, lack of adjustment for confounders, lack of detail and consistency of exposures investigated and poor reporting.

CONCLUSIONS

Childhood illness is likely to be associated with MIH. Further prospective studies of the etiology of MIH/HSPM are needed.

Association between Bone Mass and Dental Hypomineralization

The aim of this study was to examine the association between the bone mass (bone mineral content [BMC]) and hypomineralized second primary molars (HSPMs)/molar incisor hypomineralization (MIH) in 6-y-old children. This cross-sectional study was embedded in the Generation R Study, a population-based prospective cohort study, starting from fetal life until adulthood in Rotterdam, Netherlands. The European Academy of Pediatric Dentistry criteria were used to score the intraoral photographs on the presence or absence of HSPMs and MIH. Bone mass was measured with a dual-energy x-ray absorptiometry (DXA) scan. Intraoral photographs and DXA scans were available in 6,510 6-y-old children. Binary logistic regression models were used to study the association between the bone mass and HSPMs/MIH. In total, 5,586 children had their second primary molars assessed and a DXA scan made; 507 children were diagnosed with HSPM. Of 2,370 children with data on their permanent first molars, 203 were diagnosed with MIH. In the fully adjusted model, children with lower BMC (corrected for bone area) were more likely to have HSPMs (odds ratio, 1.13; 95% confidence interval, 1.02 to 1.26 per 1-standard deviation decrease). A lower BMC (corrected for bone area) was not associated with MIH (odds ratio, 1.02; 95% confidence interval, 0.87 to 1.20 per 1-standard deviation decrease). We observed a negative association between BMC (corrected for bone area) and HSPMs. No association was found between BMC (corrected for bone area) and MIH. Future research should focus on investigating the mechanism underlying the negative association between the bone mass and HSPMs. Our study, in a large population of 6-y-old children, adds the finding that BMC (corrected for bone size) is associated with HSPMs but not with MIH in childhood.

Standardised studies on Molar Incisor Hypomineralisation (MIH) and Hypomineralised Second Primary Molars (HSPM): a need

In November 2014, a review of literature concerning prevalence data of Molar Incisor Hypomineralisation (MIH) and Hypomineralised Second Primary Molars (HSPM) was performed. A search of PubMed online databases was conducted for relevant articles published until November 2014. The reference lists of all retrieved articles were hand-searched. Studies were included after assessing the eligibility of the full-text article. Out of 1078 manuscripts, a total of 157 English written publications were selected based on title and abstract. Of these 157, 60 were included in the study and allocated as 52 MIH and 5 HSPM, and 3 for both MIH and HSPM. These studies utilised the European Academy of Paediatric Dentistry judgment criteria, the modified index of developmental defects of enamel (mDDE) and self-devised criteria, and demonstrated a wide variation in the reported prevalence (MIH 2.9-44 %; HSPM 0-21.8 %). Most values mentioned were representative for specific areas. More studies were performed in cities compared with rural areas. A great variation was found in calibration methods, number of participants, number of examiners and research protocols between the studies. The majority of the prevalence studies also investigated possible aetiological factors. To compare MIH and HSPM prevalence and or aetiological data around the world, standardisation of such studies seems essential. Standardisation of the research protocol should include a clearly described sample of children (minimum number of 300 for prevalence and 1000 for aetiology studies) and use of the same calibration sets and methods whereas aetiological studies need to be prospective in nature. A standardised protocol for future MIH and HSPM prevalence and aetiology studies is recommended.