Caries Incidence Rate Definition — NDEB AFK MCQ
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Correct answer: C — The number of new carious surfaces (DFS increment) developing in a defined population over a specified follow-up period, divided by the person-time at risk
Incidence rate (incidence density) measures the rate at which new cases of disease develop in a population over time: number of new events / total person-time at risk. For dental caries, this is often expressed as the DFS (Decayed-Filled Surfaces) increment — the number of new decayed or filled surfaces developing over the observation period. This requires longitudinal follow-up (cohort study or clinical trial design). Incidence is distinct from prevalence (which includes both new and existing cases at a point in time).
Reference: Burt & Eklund – Dentistry, Dental Practice, and the Community, 7th ed., 2005