MJDF Dental Public Health — Questions and Answers
Question 1: What is the recommended fluoride concentration in water fluoridation schemes in the UK, and what is the evidence for its effectiveness?
- 5 ppm — evidence is inconclusive
- 1 part per million (1 mg/L) — systematic reviews show it reduces dental caries prevalence by approximately 26-35% in permanent teeth and 40-49% in primary teeth, with the greatest benefit for children in deprived areas (Correct answer)
- 0.1 ppm — it prevents fluorosis only
- 10 ppm — it eliminates all caries in the population
Correct answer: 1 part per million (1 mg/L) — systematic reviews show it reduces dental caries prevalence by approximately 26-35% in permanent teeth and 40-49% in primary teeth, with the greatest benefit for children in deprived areas
The optimal fluoride level for community water fluoridation in the UK is 1 ppm (1 mg/L), as established by the Water Fluoridation (England) Regulations. The 2022 Cochrane review and PHE's 2022 monitoring report for England confirm caries reduction of approximately 26-35% in permanent dentition and greater benefits in primary teeth. The effect is greatest in areas of high deprivation, making water fluoridation an important tool for reducing oral health inequalities. The Health and Care Act 2022 transferred the decision-making power for water fluoridation from local authorities to the Secretary of State for Health.
Question 2: What does the term 'inverse care law' mean in the context of dental public health?
- It means that wealthier patients receive less dental care than poorer patients
- It states that the availability of good medical or dental care tends to vary inversely with the need of the population served — those with the greatest need have the least access to care (Correct answer)
- It means that dental professionals prefer to work in deprived areas
- It describes the relationship between sugar consumption and fluoride use
Correct answer: It states that the availability of good medical or dental care tends to vary inversely with the need of the population served — those with the greatest need have the least access to care
The inverse care law was described by Julian Tudor Hart in 1971. In dental public health, it manifests as populations with the highest levels of dental disease (typically in deprived areas) having the poorest access to dental services, fewer dentists per capita, longer waiting times, and more barriers to care (financial, geographical, cultural, educational). This law explains why individual treatment-based approaches alone cannot resolve oral health inequalities, and why population-wide preventive strategies (water fluoridation, supervised brushing programmes) are essential.
Question 3: In epidemiological studies of dental caries, what does the DMFT index measure and what are its limitations?
- It measures gum disease severity and has no limitations
- DMFT measures the sum of Decayed, Missing, and Filled Teeth in the permanent dentition; limitations include not recording severity of each lesion, not distinguishing reasons for tooth loss, being cumulative and irreversible, and not capturing initial (enamel-only) caries lesions (Correct answer)
- It measures the number of dental visits per year
- DMFT measures only the number of fillings a patient has
Correct answer: DMFT measures the sum of Decayed, Missing, and Filled Teeth in the permanent dentition; limitations include not recording severity of each lesion, not distinguishing reasons for tooth loss, being cumulative and irreversible, and not capturing initial (enamel-only) caries lesions
The DMFT index (Klein, Palmer and Knutson, 1938) records the number of permanent teeth that are Decayed (untreated caries), Missing (extracted due to caries), or Filled (restored due to caries). Maximum score is 28 (excluding third molars). Limitations: it weights a small cavity the same as an extensively destroyed tooth; teeth missing for reasons other than caries (orthodontics, trauma, periodontal disease) may be incorrectly counted; it is cumulative and irreversible (cannot decrease over time); it does not capture early enamel lesions; and it may underestimate caries in populations with limited access to restorative care (low F component).
Question 4: What are the current 'Delivering Better Oral Health' (DBOH) guidelines regarding sugar consumption and caries prevention?
- Sugar has no relationship to dental caries
- Free sugars should be limited to less than 5% of total energy intake (approximately 30g/day for adults); sugar-containing foods and drinks should be restricted to mealtimes only; and sugary snacks between meals should be replaced with non-cariogenic alternatives (Correct answer)
- Sugar intake is only relevant for children under 5
- Any amount of sugar is acceptable if teeth are brushed afterwards
Correct answer: Free sugars should be limited to less than 5% of total energy intake (approximately 30g/day for adults); sugar-containing foods and drinks should be restricted to mealtimes only; and sugary snacks between meals should be replaced with non-cariogenic alternatives
Delivering Better Oral Health (PHE/OHID, 4th edition 2021) aligns with WHO and SACN recommendations: free sugars intake should be less than 5% of total energy intake. Key dietary advice for caries prevention: avoid sugar-containing foods and drinks between meals (frequency is more important than total amount), limit sugary items to mealtimes when salivary buffering is highest, use sugar-free medicines, avoid sugary drinks (including fruit juices — limit to 150 mL/day diluted at mealtimes), and do not add sugar to weaning foods. For infants, only breast milk, formula, or water should be given in bottles.
Question 5: What is the difference between 'population strategy' and 'high-risk strategy' in preventive dental public health, and which is more effective for reducing oral health inequalities?
- They are identical approaches with different names
- Population strategy targets the entire population (e.g., water fluoridation, sugar taxation) to shift the whole risk distribution; high-risk strategy identifies and targets individuals at elevated risk (e.g., fluoride varnish programmes for high-caries children). Population strategies are more effective for reducing inequalities as they do not depend on individual behaviour change or access to services (Correct answer)
- High-risk strategy is always more effective because it targets resources efficiently
- Population strategy only applies to infectious diseases, not dental caries
Correct answer: Population strategy targets the entire population (e.g., water fluoridation, sugar taxation) to shift the whole risk distribution; high-risk strategy identifies and targets individuals at elevated risk (e.g., fluoride varnish programmes for high-caries children). Population strategies are more effective for reducing inequalities as they do not depend on individual behaviour change or access to services
Geoffrey Rose's prevention paradox distinguishes these two complementary approaches. Population strategies (water fluoridation, sugar taxes, regulations on advertising) shift the entire distribution of disease risk, benefiting the whole population including those who would not seek individual care. High-risk strategies (targeted fluoride varnish, fissure sealants) identify and treat at-risk individuals. For reducing inequalities, population strategies are superior because they do not depend on individuals seeking care, being identified as high-risk, or changing behaviour — they create an environment where the healthier choice is the default.
Question 6: According to NICE guidelines, what are the recommended intervals between dental recall examinations for adults and children?
- Every 6 months for all patients regardless of risk
- For adults, the interval should be personalised between 3 and 24 months based on caries risk, periodontal status, and other factors; for children and young people under 18, the interval should be between 3 and 12 months (Correct answer)
- Annual examinations for all patients without exception
- Dental examinations are only needed when patients have symptoms
Correct answer: For adults, the interval should be personalised between 3 and 24 months based on caries risk, periodontal status, and other factors; for children and young people under 18, the interval should be between 3 and 12 months
NICE Clinical Guideline CG19 (2004, reviewed 2018) recommends variable recall intervals based on individual risk assessment. For adults (18+): the shortest interval is 3 months (high risk) and the longest is 24 months (low risk). For children and young people (<18): the shortest is 3 months and the longest is 12 months (shorter maximum because of the rapidly changing dentition, higher caries incidence, and need to establish preventive behaviours). Risk factors considered include caries history, diet, fluoride exposure, medical history, social factors, and clinical findings.
MJDF Dental Public Health
What is the recommended fluoride concentration in water fluoridation schemes in the UK, and what is the evidence for its effectiveness?