MJDF Dental Public Health

Question 1

What is the recommended fluoride concentration in water fluoridation schemes in the UK, and what is the evidence for its effectiveness?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted 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

Answer

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.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Dental Public Health