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IOTN — MFDS Part 1 MCQ

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ModerateOrthodontic PrinciplesIOTNMFDS Part 1

Which statement correctly describes the Index of Orthodontic Treatment Need (IOTN) and its use in NHS orthodontic assessment in England?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — It uses separate Dental Health and Aesthetic Components; NHS treatment is normally available at DHC grades 4 or 5, or DHC grade 3 with AC 6 or more.

Option B is correct. IOTN assesses orthodontic treatment need through two separately recorded components: the Dental Health Component (DHC, grades 1–5) and Aesthetic Component (AC, grades 1–10). Their scores are not added together. In England, NHS-funded orthodontic treatment is normally restricted to DHC grades 4 or 5, or DHC grade 3 when the AC score is 6 or more. Option E incorrectly combines the component scores. Option D describes assessment of treatment outcome rather than treatment need. Option C concerns treatment complexity, which IOTN does not principally measure. Option A describes oral-health assessment before appliance therapy; oral hygiene, caries and periodontal health affect readiness for treatment but are not components of IOTN.

Reference: NHS Business Services Authority. What is IOTN? Current NHS Dental Services guidance, accessed 26 August 2026. https://faq.nhsbsa.nhs.uk/knowledgebase/article/KA-01983/en-us