Biomarkers for Lifetime Caries-Free Status

Genes and single nucleotide polymorphisms in the pathway of saliva and dental caries: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to investigate the influence of single nucleotide polymorphisms (SNPs), related to genes in salivary composition and flow, on dental caries experience. Sixteen studies were included in the systematic review and ten in the meta-analysis. Forty-four SNPS, covering four genes (CA6, AQP2, AQP5, and MUC5B) were identified. Most of the SNPs were not associated with caries in meta-analysis. Homozygous TT genotype of the SNP CA6 rs17032907(C/T) was associated with caries [OR = 3.23(1.39-7.49)]. The pool effect of the SNPs assessed in AQP5 was associated with a reduction in the likelihood of caries [OR = 0.75(0.59-0.95)]. Considering all SNPs of salivary composition and flow, the effect allele was associated with a 75% increase in the likelihood of caries [OR = 1.75(1.06-2.89)] in the homozygous genotype. The present findings showed that the genes in salivary composition and flow can play an important role in dental caries experience.

Polymorphisms in genes expressed during amelogenesis and their association with dental caries: a case–control study

Objectives

Dental caries is a widespread multifactorial disease, caused by the demineralization of hard dental tissues. Susceptibility to dental caries is partially genetically conditioned; this study was aimed at finding an association of selected single nucleotide polymorphisms (SNPs) in genes encoding proteins involved in amelogenesis with this disease in children.

Materials and methods

In this case–control study, 15 SNPs in ALOX15, AMBN, AMELX, KLK4, TFIP11, and TUFT1 genes were analyzed in 150 children with primary dentition and 611 children with permanent teeth with/without dental caries from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) cohort.

Results

Dental caries in primary dentition was associated with SNPs in AMELX (rs17878486) and KLK4 (rs198968, rs2242670), and dental caries in permanent dentition with SNPs in AMELX (rs17878486) and KLK4 (rs2235091, rs2242670, rs2978642), (p ≤ 0.05). No significant differences between cases and controls were observed in the allele or genotype frequencies of any of the selected SNPs in ALOX15, AMBN, TFIP11, and TUFT1 genes (p > 0.05). Some KLK4 haplotypes were associated with dental caries in permanent dentition (p ≤ 0.05).

Conclusions

Based on this study, we found that although the SNPs in AMELX and KLK4 are localized in intronic regions and their functional significance has not yet been determined, they are associated with susceptibility to dental caries in children.

Clinical relevance

AMELX and KLK4 variants could be considered in the risk assessment of dental caries, especially in permanent dentition, in the European Caucasian population.

Effect of enamel-surface modifications on shear bond strength using different adhesive materials

BACKGROUND

This study aimed to investigate the effect of enamel-surface modifications on the shear bond strength between ceramic brackets bonded using different adhesive materials and the enamel surface and to identify the most suitable clinical adhesive and bonding method. Whether the non-acid-etching treatment met the clinical bond strength was also determined.

METHODS

A total of 108 extracted premolars were divided into nine groups (n = 12) based on the different enamel-surface modification techniques (acid etching, deproteinization, and wetting). Group 1 was bonded with Transbond™ XT adhesive, whereas groups 2-9 were bonded with resin-modified glass ionomer cement (RMGIC). The treatment methods for each group were as follows: groups 1 and 2, acid etching; group 3, acid etching and wetting; group 4, acid etching and deproteinization; group 5, acid etching, deproteinization, and wetting; group 6, deproteinization; group 7, deproteinization and wetting; group 8, without treatment; and group 9, wetting. The samples' shear bond strength was measured using an universal testing machine. Adhesive remnant index (ARI) was examined using a stereomicroscope. The enamel-surface morphology was observed with a scanning electron microscope. One-way ANOVA with Tukey's post-hoc test and chi-square test were used for statistical analysis, and p < 0.05 and α = 0.05 were considered statistically significant.

RESULTS

The ARIs of groups 1-5 and 6-9 were statistically significant (p = 0.000). The enamel surface of groups 1-5 was demineralized, and only a tiny amount of protein remained in groups 7 and 8, whereas a thick layer of protein remained in groups 8 and 9.

CONCLUSIONS

RMGIC adhesive did not damage the enamel surface and achieved the required clinical bond strength. The enamel surface was better treated with 5.25% sodium hypochlorite preferably under non-acid-etching conditions.

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.