Childhood oral health and disease – a multifactorial model
Associate Professor Toby Hughes
The University of Adelaide
Tooth decay is the most common chronic disease of Australian children, affecting 50% of 6 year olds. It causes pain, systemic infection, speech/learning problems, and is a predictor for poor general health. Treatment accounts for $5.3 billion in spending in Australia annually.
The role of dietary sugar in tooth decay is well established, however population lifestyle changes are difficult and costly to implement. This project will identify factors in dental plaque for use in early screening to identify high risk children, promoting targeted, less invasive, and more cost-effective interventions.
Toby Hughes, Grant Townsend, Christina Adler, Michelle Bockmann
Dental caries (tooth decay) remains the most common chronic disease affecting Australian children, despite implementation of public health initiatives such as fluoridated drinking water and toothpastes. It can cause pain and systemic infection, lead to speech and learning problems, and is a predictor for poor general health. Adverse outcomes are disproportionately present in disadvantaged segments of the Australian population. Treatment for dental caries inflicts a large economic burden on society.
The key components of this disease include an individual’s genes, their diet (especially sugar content) and their oral microbiome (the collection of bacteria in their mouth). Working with a group of young Australian twin children to capture information regarding genes and diet, we sought to learn more about the role of the dental plaque in this disease.
Overall, the project has provided early evidence of ecology-level factors in dental plaque that are implicated in disease progression and protection/recovery. This includes a core oral microbiome shared by most individuals regardless of health-status, as well as a caries-specific shift in oral ecology associated with an increased abundance and diversity of bacterial sugar-uptake pathways. We hope further investigation will identify biomarkers that can be used to predict disease risk and allow for early intervention.
Although there is a significant amount of information regarding caries risk for a few key bacterial species, little is known about the role of the ecology of the dental plaque as whole, which can contain more than 1,000 different species at any point in time. Using a cohort of well-characterised young Australian twin children to capture information regarding host genome and diet, the aims of this project were:
- Using genome-sequencing approaches, to profile species/strains of bacteria in dental plaque from 40 monozygotic (‘identical’) and dizygotic (‘non-identical’) twin pairs discordant for dental caries at 5 years of age.
- To re-profile species/strains of the dental plaque and re-score caries status in the same twin pairs 6 months and 12 months later.
Analysis of the initial samples is largely complete, and the findings to-date are summarised below:
- In the first instance, many of the same microbial genomes were found in common across all twins, representing a core oral microbiome
- Caries was associated with a change in the relative abundance of constituents of the core microbiome, where bacterial community networks were perturbed
- Sugar-fermenting bacteria were always enriched in individuals with caries, as were the abundance and diversity of sugar-uptake pathways
- Caries was also associated with the enrichment of environmental sensing and antibiotic resistance, suggesting that acid-production (a by-product of bacterial sugar metabolism and the ultimate cause of tooth enamel loss in caries) provides a selective pressure
Sequencing of the 2nd and 3rd follow-up samples has been completed and analysis is ongoing. Preliminary findings include:
- With the progression of caries, ecological perturbation is more significant
Stabilisation or a reduction in the relative severity of caries over twelve months in some individuals was associated with a shift in community profile back towards the core microbiome Overall, this project has provided early evidence of ecology-level factors in dental plaque that are implicated in diseaseprogression and protection/recovery. The final full analysis of the longitudinal plaque profiles will form the basis for a larger-scale investigation in the same twin cohort to identify biomarkers of the plaque microbiome that can be used to predict risk and allow for early intervention.
All our findings are being written up for publication in the near future.
Evolution of the Oral Microbiome and Dental Caries
Curr Oral Health Report, Published online 7 July 2017