A patient has 5 mm probing depth, 8–9 mm CAL, 5 missing teeth, and 40% generalized bone loss. The patient smokes and has diabetes. What is the correct periodontal staging and grading?

Correct answer: B. Stage IV, Grade C

• A. Stage IV is correct (5 missing teeth, 40% bone loss, complex occlusal needs). But Grade B is incorrect — smoking (>10 cigarettes/day) and uncontrolled diabetes are Grade C modifiers.
• B. Stage IV: CAL ≥5 mm, bone loss ≥33%, tooth loss due to periodontitis (5 missing teeth), complex rehabilitation needs. Grade C: rapid progression indicated by modifiers — SMOKING and DIABETES are both Grade C risk factor modifiers per the 2017 classification.
• C. Stage III requires severe CAL (≥5 mm) and bone loss — correct. But 5 missing teeth due to periodontitis pushes this to Stage IV. Grade B has bone loss/age ratio 0.25–1.0 with no modifiers. Smoking and diabetes push to Grade C.
• D. Stage III is incorrect given 5 missing teeth from periodontitis = Stage IV. Grade C is correct given smoking + diabetes as modifiers.