Hypomineralised Second Primary Molars Research Articles

"Ethnic disparities in the prevalence of Molar-Incisor-Hypomineralisation (MIH) and caries among 6-12-year-old children in Catalonia, Spain".

To study the prevalence of MIH and caries in 6- and 12-year-old schoolchildren and their association with ethnic disparities and other relevant factors. In recent years, there has been uneven improvement in school children's oral health, highlighting inequalities in access to dental care and health outcomes, particularly among ethnic minorities. The most prevalent oral disease in childhood, caries, is preventable, as its risk factors are well known. However, MIH, a common condition affecting the enamel of permanent incisors and/or molars, has no established aetiology or preventive measures. A cross-sectional study among schoolchildren was conducted in 725 children from Masnou (Barcelona, 2013) and in 577 children from Sant Andreu de Llavaneres (Barcelona, 2018-2020). Data collection was carried out by means of clinical examination and a selfreferenced questionnaire. Oral health outcomes included: presence of dental caries, presence of MIH, hypomineralised second primary molars (HSPM). All variables were analysed according to ethnic disparities and other variables such as socioeconomics, diet, hygiene habits, plaque and access to dental services. We performed multivariate Poisson regression models with robust variance to examine ethnic disparities in MIH and caries. This cross-sectional study based in Catalonia, Spain showed that there are ethnic disparities in caries as observed with other child's diseases; however, they do not seem to follow the same pattern for MIH. More studies are needed (i) to explore how MIH behaves among populations in terms of inequality; (ii) to study the aetiological factors of MIH; and (iii) to identify potential factors associated with MIH and caries that have not been studied and that may contribute to the observed ethnic disparities.

General dentists' perceptions and clinical management of hypomineralised second primary molars (HSPM) in Ireland.

This questionnaire aimed to explore how general dentists in the Republic of Ireland perceive and manage hypomineralised second primary molars (HSPM). Following ethical approval, a validated structured questionnaire containing 19 questions was sent to Irish dentists using Survey Monkey. Questions on awareness, dentist's experience, barriers to care and clinical scenarios with different treatment options were included. Binary outcomes and independent variables were compared using logistic regression analysis (α = 5%). Responses from 279 general dentists were analysed. The majority of dentists were aware of HSPM (72%) and most dentists felt confident in diagnosing HSPM (71%). Dentists who had practiced for ≥ 15 years were significantly more likely to document HSPM frequently compared to those with less experience (OR 0.29; p = 0.012). No significant association was found between confidence in HSPM diagnosis and other variables, such as age group, years of practice and workplace. Dentists not working in private practice reported to be less comfortable in the management of HSPM (OR 0.49; p = 0.030). The most cited barrier to management of HSPM was child's behaviour. A broad variation was observed in the clinical scenarios, in particular when treatment planning more severe HSPM. In general, Irish dentists are aware of HSPM and are confident in diagnosis and management. Variation existed in treatment options reflecting the disparity that exists in clinical management.

Predictive Value of Hypomineralization of Second Primary Molars for Molar Incisor Hypomineralization and Other Relationships between Both Developmental Defects of Dental Enamel.

Molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM) are dental enamel developmental defects with significant prevalence and psychophysical impact, posing a public health concern. We examined the relationship between HSPM and MIH in 426 children aged 7 to 10 years (213 with MIH, 213 without MIH). The frequency of HSPM was higher in children with MIH (37.1% vs. 11.3%, p < 0.001). However, there was no correlation between MIH severity and presence of HSPM (p = 0.296). In patients with both defects (n = 79), 90% of severe MIH cases were associated with severe HSPM, while 87.8% of mild MIH cases were associated with mild HSPM (p < 0.001). The involvement of permanent incisors by MIH was not influenced by the presence of HSPM or HSPM severity. HSPM exhibited a positive predictive value of 76.7, negative predictive value of 58.8, sensitivity of 37.1% (95% CI = 30.6-43.6%), and specificity of 88.7% (95% CI = 84.5-93%). The odds ratio for MIH based on HSPM was 4.64 (95% CI). HSPM may serve as a predictor of MIH, but its absence does not rule out the occurrence of MIH. The results highlight the need for surveillance programs in children presenting with HSPM to facilitate early diagnosis and preventive measures for MIH-related complications.

Prenatal, perinatal and postnatal risk factors associated with hypomineralised second primary molars – A cross-sectional study

ObjectiveTo evaluate the prenatal, perinatal, and postnatal risk factors associated with hypomineralised second primary molars (HSPM) in four to seven-year-old children. MethodsThis cross-sectional study comprised 300 children (100 with HSPM and 200 controls). Four-to-seven-year-old children were selected after examining for the presence of demarcated hypomineralised lesions in second primary molars using an adapted version of the European Academy of Pediatric Dentistry (EAPD) criteria 2003. Children who exhibited signs of HSPM were selected as the subjects HSPM group), and those children without HSPM were taken as controls. Only patients with documented medical records were included to evaluate the possible risk factors. Information regarding the children's maternal health during pregnancy and postnatal health was recorded using a structured proforma. ResultsMothers suffering from systemic illnesses during pregnancy were significantly more in the HSPM group than controls (61% vs. 13.5%; p < 0.001). Presence of early childhood illnesses (80% vs. 19.0%; p < 0.001), hospital admission more than once in three months (45% vs. 4.5%; p < 0.001), and frequent intake of antibiotics (42% vs. 4.0%; p < 0.001) were significantly more in children with HSPM than the controls. ConclusionA significant association between maternal illnesses during pregnancy and HSPM was observed. Children with HSPM experienced more medical conditions than their unaffected counterparts, particularly during the post-natal period.

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

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. To determine the prevalence of MIH and HSPM in south-western France and explore the distribution of hypomineralised lesions on permanent and primary molars. 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. 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). Molar-incisor hypomineralisation and HSPM have three main asymmetrical characteristics: tooth location, severity of hypomineralisation and number of teeth affected.

Are Molar-Incisor Hypomineralization and Hypomineralized Second Primary Molars Predictive of Dental Caries?: A Systematic Review.

To estimate the prevalence of dental caries among children affected concomitantly with molar-incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM).Electronic databases, including Medline via PubMed, Cochrane Library, Scopus, and Science Direct, were searched. Studies written in English involving children with MIH-HSPM and dental caries were considered eligible. Two reviewers extracted the data according to the PRISMA statement and assessed the bias risk with the Newcastle-Ottawa Scale (NOS) criteria.Out of 535 studies identified in the initial research, only two articles were included in the present review. A significant association between MIH-HSPM and dental caries in permanent dentition was reported in the two included records (AOR: 3.70; p < 0.001). Children with MIH-HSPM expressed significantly higher DMFT and PUFA values than children without MIH-HSPM. However, dmft values did not differ significantly between children with and without HSPM (1.79 [2.4] vs. 1.78 [2.5]; 1.88 [2.73] vs. 1.59 [2.53], respectively.MIH-HSPM lesions were correlated with a higher prevalence and more severe carious lesions in permanent dentition. However, the results should be interpreted cautiously because the findings were generated by only two studies performed by the same authors. Thus, further well-designed studies are highly recommended.

Association between hypomineralization of deciduous and molar incisor hypomineralization and dental caries

This study aimed to evaluate the association between the severity of hypomineralized second primary molars (HSPM), molar-incisor hypomineralization (MIH) and dental caries in children. 450 children between the ages of 6 and 7 years were included in this cross-sectional study. A calibrated examiner classified the enamel hypomineralizations and dental caries lesions using the MIH and HSPM and the Nyvad criteria, respectively. The primary outcome was the severity of MIH according to the severity of HSPM. Statistical analysis was performed using the generalized linear model and ordinal logistic regression. The prevalence of concomitant MIH and HSPM was 26% sex and age adjusted. Mild enamel defects were more frequent than severe enamel defects. An association was found between the severity of MIH and HSPM, both for mild defects (OR=87.54; 95%CI: 55.87, 137.17) and severe defects (OR=82.15; 95%CI: 45.72, 147.61). The severity of hypomineralization in permanent molars was associated with the activity of dental caries lesions (OR=29.85; 95%CI: 12.95, 68.83). To conclude, there is a strong association between the severity of HSPM and MIH, which is more significant in the presence of active dental caries lesions.

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

PurposeThe 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.MethodsThe 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.ResultsAmong 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).ConclusionConsidering 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.

Childhood malnutrition and hypo mineralized molar defects ;a cross sectional study, Egypt.

Background: Malnutrition is well-known to yield high morbidities and it has pre-eruptive and post-eruptive consequences. The objective of the study was to evaluate the prevalence of Hypomineralized Second Primary Molars (HSPM), Molar Incisor Hypomineralization (MIH) and dental caries in malnourished children, as well as addressing the relation between types of malnutrition and the dental morbidities. Methods: This is a cross sectional analytical study. A consecutive sample of 54 malnourished cases aged 5-10 years and presented to the Outpatient Clinic of Pediatric Dentistry Department, Faculty of Dentistry, Cairo University across 6 months period were examined for HSPM, MIH - using the European Academy of Pediatric Dentistry criteria - and dental Caries using def/ DMF indices. Outcomes were the presence or absence of MIH and HSPM and their levels measured as percentage as well as Caries Indices. Exposures were types of malnutrition and the socioeconomic status. Results : The mean age of study participants was 7.10 ± 1.34 years. HSPM and MIH were found in 47.2% and 45.2% of the study participants respectively, while dental caries was observed in 83% and 64.3% for primary and permanent teeth respectively. There was co-occurrence between HSPM and MIH in 39% of the cases. HSPM level was significantly different in various types of malnutrition. It showed significant difference between the stunted group (median HSPM of 14.2%) and the overweight or obese group (median HSPM of 0.0%) (P value 0.01). MIH level showed significant differences between the stunted group (median MIH of 19.4%) and overweight or obese group (median MIH of 0.0%) (p value 0.001), as well as between the stunted group (median MIH of 19.4%) and wasted group (median MIH of 0.0%) (p value 0.025). Conclusions : Malnourished children have high prevalence of dental abnormalities. HSPM could expect the presence of MIH.

Childhood malnutrition and hypo mineralized molar defects ;a cross sectional study, Egypt

Background: Malnutrition is well-known to yield high morbidities and it has pre-eruptive and post-eruptive consequences. The objective of the study was to evaluate the prevalence of Hypomineralized Second Primary Molars (HSPM), Molar Incisor Hypomineralization (MIH) and dental caries in malnourished children, as well as addressing the relation between types of malnutrition and the dental morbidities. Methods: This is a cross sectional analytical study. A consecutive sample of 54 malnourished cases aged 5-10 years and presented to the Outpatient Clinic of Pediatric Dentistry Department, Faculty of Dentistry, Cairo University across 6 months period were examined for HSPM, MIH – using the European Academy of Pediatric Dentistry criteria - and dental Caries using def/ DMF indices. Outcomes were the presence or absence of MIH and HSPM and their levels measured as percentage as well as Caries Indices. Exposures were types of malnutrition and the socioeconomic status. Results : The mean age of study participants was 7.10 ± 1.34 years. HSPM and MIH were found in 47.2% and 45.2% of the study participants respectively, while dental caries was observed in 83% and 64.3% for primary and permanent teeth respectively. There was co-occurrence between HSPM and MIH in 39% of the cases. HSPM level was significantly different in various types of malnutrition. It showed significant difference between the stunted group (median HSPM of 14.2%) and the overweight or obese group (median HSPM of 0.0%) (P value 0.01). MIH level showed significant differences between the stunted group (median MIH of 19.4%) and overweight or obese group (median MIH of 0.0%) (p value 0.001), as well as between the stunted group (median MIH of 19.4%) and wasted group (median MIH of 0.0%) (p value 0.025). Conclusions : Malnourished children have high prevalence of dental abnormalities. HSPM could expect the presence of MIH.

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.

Prevalence of hypomineralised second primary molars (HSPM): A systematic review and meta-analysis.

To evaluate the prevalence of HSPM worldwide on a child and a tooth level and investigate the influence of diagnostic criteria on the prevalence of HSPM. A comprehensive literature search was performed through MEDLINE/PubMed, Scopus, and Web of Science databases. The grey literature was also screened as were the reference lists of included studies. An adaptation of the Newcastle-Ottawa Scale was used to evaluate the quality of the studies. A meta-analysis was performed to determine the pooled prevalence of HSPM. The search strategy identified 1,988 articles, 487 were retrieved for full-text evaluation, and 37 studies were included in the meta-analysis (32 for child and 23 for tooth level prevalence), providing data from 26,805 individuals and 81,107 molars. The prevalence of HSPM was 6.8% (95% CI 4.98%-8.86%) on a child level and 4.08% on a tooth level (95% CI=2.80%-5.59%). The diagnostic criteria used did not seem to influence the prevalence results (P>.05). The majority of the papers (75%) showed a low-to-moderate risk of bias. There was a broad variation in the prevalence reported that may be attributed to differences in the study population. The present meta-analysis showed a HSPM prevalence worldwide of 6.8% on a child level and 4.1% on a tooth level.

Hypomineralisation of second primary molars and primary canines: Prevalence and description of lesions in a population of 153 patients visited at a hospital paediatric dentistry service.

The enamel defects of Molar-Incisor Hypomineralisation (MIH) share clinical characteristics with hypomineralised second primary molars (HSPM) and hypomineralised primary canines (HPC). The main objective of this study is to determine the prevalence of these entities in a population of patients in a hospital dentistry service. The secondary objectives are to know the number and distribution of lesions, classify them according to their degree of severity and to know which dental surfaces are most affected. A cross-sectional and observational prevalence study was carried out over a 32-day period, guided by the diagnostic criteria of the European Academy of Paediatric Dentistry (EAPD) together with the descriptive study of the lesions. Healthy patients between 30-42 months and who had all erupted teeth were included. Out of a total of 153 patients, 29 presented HSPM (18.95%) and 17 HPC (11.11%). Check-ups were made on 116 second primary molars (SPM) and 116 primary canines (PC), obtaining 81 HSPM (69.82%) and 31 HPC (26.72%). The lesions observed were mild in 60 molars (74.07%) and in 27 canines (87.09%). As for the 405 surfaces checked, 168 showed HSPM (41.48%) and 43 HPC (10.61%). The prevalence of HSPM and HPC varies depending on the population studied. It was observed that SPM were affected more often than PC, with the occlusal and buccal surfaces being the most affected, and the majority of the lesions presenting a low degree of severity.

Schweregrade der Milchmolaren-Hypomineralisation und Molaren-Inzisiven- Hypomineralisation in Zahnarztpraxen

Background: Deciduous molar hypomineralization (DMH) and molar-incisor hypomineralization (MIH) represent dental defects in primary and secondary dentition and have been diagnosed worldwide. The aim of this retrospective study was to evaluate pseudonymized DMH and MIH results of eight private pedodontists' practices in northern Germany.Methods: The investigators were calibrated before the study began. All subjects showed either signs of DMH, MIH, or both DMH and MIH. Incisors were only included if a molar was also affected. Hypomineralized lesions on hypomineralized second primary molars (HSPM) and MIH were classified according to Wetzel and Reckel (1991). Severity grade (SG) I clinically corresponded to individual cream to brown areas on occlusal surfaces/cusp tips with preserved tooth morphology, while SG III corresponded to large yellowish-brown areas over the entire tooth area with defects in crown morphology and severe enamel loss, coupled with high tooth sensitivity. The evaluation was primarily descriptive.Results: A total of 338 patients were examined. Gender was nearly equally distributed (male: n=170, 50.3 %; female: n=168, 49.7 %). The mean age was 7.1 (2.84) years (standard deviation [SD]) [range 3.0-18.0]. SG I was most common in both DMH (76.6 %) and MIH (76.7 %). SG III was observed most frequently on the occlusal surface in DMH (39.5 %) and MIH (34.9 %).Conclusion: The evaluation showed a low occurrence of SG III in permanent and deciduous teeth in patients with DMH and MIH. The second primary molar and first permanent molar showed the greatest severity of DMH and MIH. There was no correlation between DMH and MIH. In contrast, a statistically significant correlation between the number of affected tooth surfaces and the severity of the disease in DMH and MIH could be shown.Keywords: Deciduous molar hypomineralization, DMH, Molar-incisor hypomineralization, MIH, Severity

The Relationship between Hypomineralized Second Primary Molars and Molar Incisor Hypomineralization in a Group of School-Aged Children in Turkey

Abstract Objective This study aims to evaluate the relationship between hypomineralized second primary molars (HSPMs) and molar incisor hypomineralization (MIH) and to determine the prevalence of HSPM in different severities of MIH. Materials and Methods The study included a total of 345 children aged 7 to 11, affected with MIH at various severities. Scoring for HSPM defects was adapted according to the European Academy of Pediatric Dentistry diagnostic criteria and applied by a single calibrated examiner. Comparative evaluation of HSPM at various MIH severities was tested using a single variable logistic regression analysis. An odds ratio at a 95% confidence interval was used to test the relation between HSPM and MIH. Results The prevalence of HSPM was 61.7% in MIH-affected children, whereas it was 2.6% in the control group (p &lt; 0.001). The presence of HSPM and the increase in the number of affected teeth significantly raised the odds of the occurrence of MIH. HSPM prevalence was higher in children affected with milder MIH compared to those affected severely. The recorded defects were common as white-cream demarcated opacities without any loss of structure. Conclusion The prevalence of HSPM was significantly higher in children presenting MIH. Therefore, hypomineralization on the primary second molars pointed to an association between MIH and HSPM. For an early diagnosis of MIH, children presenting HSPM whose first permanent molars have not erupted yet should be followed up at regular intervals by pediatric dentists.

Management of molar-incisor hypomineralisation by general dental practitioners - part one: diagnosis.

Introduction Molar-incisor hypomineralisation (MIH) affects one in six children in the UK. For the majority of patients who have mild MIH, this should be managed in primary care.Aims To assess UK-based general dental practitioners' (GDPs) ability to diagnose MIH when presented with multiple clinical vignettes.Design An electronic vignette survey was designed with use of clinical photographs - six cases had MIH and/or hypomineralised second primary molars (HSPMs) (seven possible diagnoses). Four control cases showing caries, fluorosis, amelogenesis imperfecta and dentinogenesis imperfecta were also included. Participants were UK-based GDPs. The survey was distributed by email and across social media platforms. Data collection occurred between February and May 2019.Results Seventy-six GDPs completed the survey; 68.4% (n = 52) of participants were female and 83% (n = 63) of participants graduated after the year 2000. The number of accurate diagnoses for each case were as follows - mild MIH (molars/incisors) 65.79%; mild MIH (molars only) 3.95%; HSPM and MIH (HSPM result) 0%; HSPM and MIH (MIH result) 50%; severe MIH (post-eruptive breakdown) 63.16%; severe MIH (caries) 31.58%; HSPM 3.95%.Conclusion GDPs are able to accurately diagnose MIH best when both incisors and molars are affected and caries is not present.

Non-invasive treatment approach for hypomineralised second primary molars using preformed metal crowns: results after 1-year follow-up.

To evaluate the clinical and radiological outcome of Hypomineralised Second Primary Molars (HSPM) treated with Preformed Metal Crowns (PMC) using the Hall Technique (HT). This prospective cohort study included healthy children presenting at the pediatric dental clinic of the University Hospitals Leuven (Belgium) with at least one primary molar affected by HSPM. The clinical and radiological situation at baseline and after a follow-up of 1year was registered in detail using standardized criteria. After plaque removal and gentle drying, PMCs (3M™ ESPE™ Stainless Steel Crowns) were fitted without administration of local anaesthesia nor tooth preparation. Strict outcome criteria, including gingival health condition, were applied. Informed consent was obtained for all individual participants. The study was approved by the institutional Ethics Committee. A total of 39 PMCs with a follow-up of 12months, placed in 15 patients (7 boys and 8 girls), were included. The mean age of the patients at the time of fitting the PMC was 4.6 ± 1.1years (range: 3-7). None of the PMCs was lost nor failed. Clinical outcome was considered fully successful in 64.1%, radiological outcome in 93.3% of the cases; all other cases were rated as acceptable. The main reason for not being categorized as fully successful was deterioration of the gingival condition. Overall, the treatment was well tolerated and accepted by the patients. PMCs fitted using the HT represent an acceptable and well-tolerated treatment option for the management of HSPM. Gingival condition should be incorporated in outcome assessment.

Association between demarcated enamel hypomineralization on second primary molars and dental caries in childhood

Hypomineralized Second Primary Molars (HSPM) is the name used to describe the presence of demarcated enamel hypomineralization in second primary molars. HSPM has been compared with Molar Incisor Hypomineralization (MIH) as regards its clinical appearance and consequences. The aim of this study was to investigate associations between HSPM and dental caries in childhood. It was a cross-sectional populationbased study that included 216 children aged 4-6 years from public schools in Botelhos, Brazil. Children with all second primary molars erupted were eligible for participation. Clinical examination was performed by one calibrated examiner. HSPM was recorded according to modified European Academy of Paediatric Dentistry criteria. The main outcome was dental caries experience as indicated by the dmft index (%dmft&gt;0) according to WHO criteria. Chi-square test and Logistic Regression Model were used to adjust the results for effects of covariates Among the 216 children examined, 22.2% presented HSPM. After adjustment for logistic regression, children with HSPM were found to have a 2.28 times greater chance of presenting dental caries. Our results reinforce the importance of HSPM in caries development in children, which should be considered by public health dentists in the process of planning actions aimed at this population.

Structural and chemical enamel characteristics of hypomineralised second primary molars.

Although hypomineralised second primary molars (HSPM) are considered belonging in the same entity as molar incisor hypomineralisation (MIH), the structure and chemistry of their defected enamel have not been described. We aimed to study these in justifying any similarities with MIH. Nine HSPM and five first permanent molars with MIH were either fractured or sectioned longitudinally through their defective enamel and examined by scanning electron microscopy. Relative amounts of calcium (Ca), phosphorus (P), oxygen (O), carbon (C) and the Ca:P ratio were calculated in the primary molar samples by energy -dispersive spectrometry. Rod width was deficient in the defected enamel of HSPM resulting in wide interrod spaces and suggesting similarities to permanent enamel structure in MIH. In areas with breakdown, cracks and disrupted coherence between enamel rods were more marked. Differences in Ca, P, O, C and Ca:P ratio between hypomineralised and sound enamel in HSPM followed the same trend as in MIH without reaching statistical significance. Marked structural differences between sound and hypomineralised enamel of HSPM and similarity to MIH enamel were verified.

Prevalence of molar-incisor-hypomineralisation (MIH) among 6-12-year-old children in Central Hesse (Germany).

The aim of the present cross-sectional study was to assess and compare the prevalence of MIH among 6-12-year-old school children living either in a rural area of Central Hesse (Germany) or in the city of Frankfurt on the Main (Germany). A possible association between hypomineralised second primary molars (HSPM) and MIH was investigated. Furthermore, the MIH prevalence data of the rural area were compared with those of a previous study conducted in this area in the school year 2002/2003. In the school year 2014/2015, 2103 children (6-12 years of age) were examined during the annual school-based dental examinations prescribed by law at nine schools in the rural area of Central Hesse (LDK) and five schools in the city of Frankfurt on the Main (Ffm). Eight previously calibrated dentists working for the public healthcare authorities assessed the prevalence of HSPM/MIH (EAPD criteria/severity scale by Wetzel and Reckel) and the caries experience (dmft/DMFT). The prevalence of HSPM/MIH amounted 3.2%/9.4% in LDK and 2.9%/17.4% in Ffm. In the majority of cases, children with MIH had demarcated opacities. In LDK, hypomineralised first permanent molars were most commonly affected by severity degree 2, whereas in Ffm, severity degree 1 was predominant. Children suffering from HSPM had an odds ratio of 11.32 (95% CI: 6.73-19.03) for having MIH as well. Compared with the results of 2002/2003 in LDK (prevalence of MIH 5.9%), the MIH prevalence increased by 3.5% in the rural area. All in all, the caries experience among children under investigation was low (DMFT 0.14-0.15). MIH may be diagnosed in school children living in different areas of Germany with regional variations (rural-urban comparison). The presence of HSPM is of predictive value for MIH. The increasing number of hypomineralised first permanent molars over 12 years of time in the rural area indicates a need for further investigation on the aetiology of MIH.