Community Dentistry
What this domain tests
This domain tests epidemiology, oral health needs assessment, program planning, oral health promotion, workforce and access issues, and ethics. Items often ask which measure or study design answers a community question.
Core rules and concepts
- The DMF index counts decayed, missing, and filled permanent teeth; dmf is used for primary teeth. Do not mix the two.
- Prevalence is the proportion with disease at a point in time; incidence is the number of new cases over a period. Attack rate and relative risk help compare groups.
- Cross-sectional studies measure exposure and outcome at one time. Cohort studies follow exposed and unexposed groups. Randomized controlled trials provide the strongest causal evidence when feasible.
- Sensitivity detects true cases; specificity detects true non-cases. Positive predictive value depends on prevalence.
- The Ottawa Charter emphasizes healthy public policy, supportive environments, community action, personal skills, and reorientation of health services.
- The common risk factor approach targets shared determinants such as sugar, tobacco, alcohol, and hygiene rather than single diseases.
- Program planning includes needs assessment, objectives, resources, implementation, and evaluation.
Worked example
A school district has high child caries prevalence. A survey shows many untreated lesions and low sealant use. The reasoning is to plan a school-based sealant and fluoride varnish program with parental education, then evaluate with pre- and post-program dmft or sealant retention. Screening alone is insufficient because it identifies disease without preventing it.
Traps that cost marks
Do not confuse prevalence with incidence. Do not use DMF for primary teeth. Do not assume screening reduces caries by itself. Ignore social determinants and access barriers at your peril. Also remember that predictive value changes with prevalence even when sensitivity and specificity are stable.