17.2 Dental Public Health & Epidemiology
Key Takeaways
- Prevalence is the proportion of a population with a condition at a point in time, while incidence is the rate of new cases arising over a period — caries surveys almost always report prevalence and mean DMFT
- DMFT is used for the permanent dentition and dmft for the primary dentition; the Significant Caries Index reports the mean DMFT of the worst-affected third of the population and exposes the skew that a whole-population mean hides
- Rose's prevention paradox explains why a small shift across a whole population prevents more disease than intensive effort directed only at high-risk individuals, even though most of those who shift gain nothing themselves
- Water fluoridation schemes in England target about one part per million of fluoride; the Health and Care Act 2022 transferred responsibility for those schemes from local authorities to the Secretary of State for Health and Social Care
- The common risk factor approach tackles sugar, tobacco, alcohol, stress, injury and hygiene once, because those same risks drive caries, periodontal disease, oral cancer, obesity, diabetes and cardiovascular disease
Measuring Oral Disease
Outcome C10.5 asks candidates to demonstrate the ability to take a population approach, and that begins with knowing what the numbers mean.
| Measure | Definition | Note |
|---|---|---|
| Prevalence | The proportion of a defined population with the condition at a point in time | What caries surveys report |
| Incidence | The number of new cases arising in a defined population over a defined period | Needs longitudinal follow-up |
| DMFT / DMFS | Decayed, Missing and Filled Teeth or Surfaces, permanent dentition | Capital letters for permanent teeth |
| dmft / dmfs | The same index for the primary dentition | Lower case for primary teeth |
| Significant Caries Index (SiC) | The mean DMFT of the worst-affected one-third of the population | Reveals the skew hidden by a low population mean |
| Care Index | F / DMFT, expressed as a percentage — the proportion of disease that has been treated | A measure of access, not of health |
| Root Caries Index | Root surfaces decayed or filled as a proportion of root surfaces at risk | Denominator matters in an ageing population |
| BPE, CPI, PSR | Periodontal screening measures used at individual and population level | BPE is a screening tool only |
Why the mean deceives: in England the mean dmft in five-year-olds is low, but the disease is concentrated in a minority of children — most have none, and a small group has a great deal. A policy built on the mean will miss those children entirely, which is exactly what the Significant Caries Index was designed to expose.
Where UK data comes from
- The National Dental Epidemiology Programme in England surveys five-year-olds and other age groups on a rolling basis and reports by local authority, making inequality visible at a level where action can be taken.
- The decennial Adult Dental Health Survey and the Children's Dental Health Survey provide the deep national picture across the UK nations.
- Hospital episode data on extractions under general anaesthesia in children is a widely used and politically salient indicator, because tooth decay remains a leading cause of hospital admission in young children.
Inequality and the Social Gradient
Oral disease follows a social gradient: at every step down the socio-economic scale, disease is more common and more severe. Two ideas explain the policy response.
- The inverse care law (Tudor Hart): the availability of good medical care tends to vary inversely with the need of the population served. In dentistry it appears as fewer NHS practices accepting new patients in the most deprived areas.
- Proportionate universalism (Marmot): actions should be universal, but delivered with an intensity proportionate to need. Targeting only the worst-off misses the bulk of disease, which sits in the large middle of the distribution, while a purely universal service widens the gap because the better-off take it up first.
Population-Wide Versus Targeted Approaches (Outcome C10.4)
Rose's prevention paradox: a preventive measure that brings large benefit to the population often brings little to each participating individual. Shifting the whole distribution of sugar intake slightly downward prevents more caries than intensive intervention with the highest-risk children alone — even though almost every individual who shifts gains nothing they will ever notice.
| Approach | Examples in the UK | Strengths and weaknesses |
|---|---|---|
| Whole population | Water fluoridation; the Soft Drinks Industry Levy (in force since April 2018); advertising and promotion restrictions; sugar reformulation programmes; food labelling | Reaches everyone including those who never attend a dentist; reduces inequality; but is politically contested and slow to legislate |
| Targeted (community) | Childsmile in Scotland and Designed to Smile in Wales — supervised toothbrushing and fluoride varnish programmes in nurseries and schools in areas of high need | Efficient use of resource, strong evidence base; but risks stigma and can miss eligible children |
| High-risk (individual) | High-fluoride toothpaste, four-times-yearly varnish, dietary counselling in the dental surgery | Highly effective per person treated; but only reaches attenders, so it can widen inequality |
The three are complements, not alternatives, and a good answer in an SBA stem usually recognises that a population measure and an individual measure are both required.
Water fluoridation
Community water fluoridation adjusts fluoride to about one part per million (1 mg/L). The York Review (2000) found evidence of caries reduction alongside a dose-related increase in mostly mild dental fluorosis, and subsequent UK monitoring reports have continued to find reductions in caries experience and in hospital extractions, with the largest absolute benefit in the most deprived areas. Under the Health and Care Act 2022, responsibility for fluoridation schemes in England transferred from local authorities to the Secretary of State for Health and Social Care, which was intended to remove the local barriers that had stalled new schemes.
The common risk factor approach
Sheiham and Watt's common risk factor approach argues that targeting a small number of shared risks — sugar, tobacco, alcohol, stress, injury and hygiene — addresses caries, periodontal disease, oral cancer, obesity, diabetes and cardiovascular disease simultaneously, and does so through the sectors that actually control them: food policy, education, housing and transport. It is the reason oral health promotion is integrated with general health promotion rather than run as a separate campaign.
Health promotion frameworks
The Ottawa Charter (1986) sets out five action areas that still structure UK policy: build healthy public policy, create supportive environments, strengthen community action, develop personal skills, and reorient health services. Note that only the last two involve the health service directly — most of what determines oral health lies outside the surgery.
Legal Principles Relevant to Dentistry and Public Health (Outcome C10.2)
| Instrument | Relevance |
|---|---|
| Health and Care Act 2022 | Transferred water fluoridation responsibility in England to the Secretary of State; established integrated care boards, which commission dental services |
| Soft Drinks Industry Levy | A fiscal public health measure, in force since April 2018, that drove substantial reformulation of soft drinks |
| Equality Act 2010 | Anticipatory duty to make reasonable adjustments; relevant to access as a public health issue |
| Health and Social Care Act 2008 (Regulated Activities) Regulations 2014 | CQC registration and the statutory duty of candour in England |
| The Dentists Act 1984 | Restricts the practice of dentistry to registrants and underpins prosecution of illegal practice, including illegal tooth whitening |
| NHS regulations for dental charges and contracts | Determine who pays, who is exempt, and how activity is commissioned — a direct determinant of access |
A survey of 1,000 five-year-olds reports a mean dmft of 0.8, but 70% of the children are caries-free. Which index best describes the burden carried by the affected minority?
A commissioner asks whether to fund an intensive fluoride varnish programme for the 5% of children at highest caries risk, or a supervised toothbrushing programme across all nurseries in the area. What does Rose's prevention paradox suggest?
Which statement about community water fluoridation in England is correct?
Which policy best illustrates the common risk factor approach in oral health?