Periodontitis — ORE Part 1 MCQ

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HardPeriodontologyPeriodontitisORE Part 1

A 40-year-old patient has Stage III Grade C periodontitis. Which of the following features best defines Grade C?

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

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Correct answer: D — Evidence of disease progression with bone loss/age ratio >1.0

Explanation lettering: B = shown as A · C = shown as B · D = shown as C · A = shown as D

Grade C periodontitis is defined by rapid bone loss relative to age. Using SDCEP guidance, Grade is calculated as: % bone loss at worst site ÷ age in years. Grade C is assigned when this ratio exceeds 1.0—indicating the bone loss percentage is greater than the patient's age. For example, a 40-year-old with >40% bone loss would be Grade C. Option A correctly restates this criterion. Distractors B and D represent Grade B and Grade A respectively (using the intermediate and low ratio thresholds). Options C and E confuse grading with progression monitoring and biofilm phenotype classification, neither of which defines the Grade.

Reference: Scottish Dental Clinical Effectiveness Programme (SDCEP). Prevention and Treatment of Periodontal Diseases in Primary Care. 2nd edition, 2025. https://www.periodontalcare.sdcep.org.uk/guidance/diagnosis/establishing-a-periodontal-diagnosis/periodontitis/