Our results should raise concerns about the existing social inequalities in dental caries and should encourage development of dental caries prevention strategies. New knowledge about the distribution of oral health inequalities between districts should be used to target the right audience for these strategies.

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.

Prior studies suggest dental caries traits in children and adolescents are partially heritable, but there has been no large-scale consortium genome-wide association study (GWAS) to date. We therefore performed GWAS for caries in participants aged 2.5–18.0 years from nine contributing centres. Phenotype definitions were created for the presence or absence of treated or untreated caries, stratified by primary and permanent dentition. All studies tested for association between caries and genotype dosage and the results were combined using fixed-effects meta-analysis. Analysis included up to 19 003 individuals (7530 affected) for primary teeth and 13 353 individuals (5875 affected) for permanent teeth. Evidence for association with caries status was observed at rs1594318-C for primary teeth [intronic within ALLC, odds ratio (OR) 0.85, effect allele frequency (EAF) 0.60, P 4.13e-8] and rs7738851-A (intronic within NEDD9, OR 1.28, EAF 0.85, P 1.63e-8) for permanent teeth. Consortium-wide estimated heritability of caries was low [h2 of 1% (95% CI: 0%: 7%) and 6% (95% CI 0%: 13%) for primary and permanent dentitions, respectively] compared with corresponding within-study estimates [h2 of 28% (95% CI: 9%: 48%) and 17% (95% CI: 2%: 31%)] or previously published estimates. This study was designed to identify common genetic variants with modest effects which are consistent across different populations. We found few single variants associated with caries status under these assumptions. Phenotypic heterogeneity between cohorts and limited statistical power will have contributed; these findings could also reflect complexity not captured by our study design, such as genetic effects which are conditional on environmental exposure.

The aim of this study was to investigate potential differences in caries prevalence of children from ethnic minority groups compared to native Dutch children and the influence of socio-economic status (SES) and parent-reported oral health behaviour on this association. The study had a cross-sectional design, embedded in a population-based prospective multi-ethnic cohort study. 4,306 children with information on caries experience, belonging to 7 different ethnic groups, participated in this study. The decayed, missing, and filled teeth (dmft) index was assessed at the age of 6 and categorized in two ways for analysis: children without caries (dmft = 0) versus any caries experience (dmft >0) and children without caries (dmft = 0) versus children with mild caries (dmft = 1-3) or severe caries (dmft >3). Compared to native Dutch children, children with a Surinamese-Hindustani, Surinamese-Creole, Turkish, Moroccan, and Cape Verdean background had significantly higher odds for dental caries. Especially the Surinamese-Hindustani, Turkish, and Moroccan group had significantly higher odds for severe dental caries. Household income and educational level of the mother explained up to 43% of the association between ethnicity and dental caries, whereas parent-reported oral health behaviour did not mediate the association. Alarming disparities in caries prevalence between different ethnic (minority) groups exist, which cannot be fully explained by social inequalities. Public health strategies can apply this new knowledge and specifically focus on the reduction of ethnic disparities in oral health. More research is needed to explain the high caries prevalence among different ethnic minority groups.

Oral health-related quality of life (OHRQOL) is the perceived impact of one's own oral health on daily life. Oral diseases influence children's OHRQOL directly, but OHRQOL might also be related to oral health experiences from the past. We investigate the relation between dental caries at the age of 6 with OHRQOL assessed at the age of 10. This study was conducted within the Generation R Study, a population-based prospective cohort study. Caries experience was assessed with the decayed, missing, and filled teeth index (dmft) at a median age of 6.09 years (90% range: 5.73-6.80). OHRQOL was assessed with a short form of the Child Oral Health Impact Profile at the children's age of 9.79 years (9.49-10.44). In total, 2,833 children participated in this study, of whom 472 (16.6%) had mild caries (dmft 1-3) and 228 (8.0%) had severe caries (dmft >3). The higher the dmft score at the age of 6, the lower the OHRQOL at the age of 10 (p < 0.001). The children with severe caries at the age of 6 had significantly higher odds of being in the lowest OHRQOL quartile at the age of 10 (OR = 1.69; 95% CI: 1.17-2.45). Our study highlights the importance of oral health during childhood, because those who get a compromised start to oral health are much more likely to follow a trajectory which will lead to poor oral health (-related QOL) later. OHRQOL is not only related to current oral health experiences but also to oral health experiences from the past.