Which finding most strongly supports a Stage IV diagnosis in the 67-year-old patient described (8 mm pocket depth with mobility)?

• A. A 4 mm pocket depth with no mobility
• B. An 8 mm pocket depth with class 2 mobility
• C. A 2 mm pocket depth with no mobility
• D. A 6 mm pocket depth with no mobility

Answer: (B)

Advanced periodontitis presents with features that reflect both severe tissue destruction and functional impairment. When a tooth shows a deep periodontal pocket alongside mobility, it signals that the supporting structures are significantly compromised and the tooth is unstable under functional forces. This combination is a hallmark of Stage IV, which involves substantial destruction and the need for complex, multidisciplinary treatment to manage function and prognosis.

The other scenarios show shallower pockets or the same depth without mobility, which indicate less advanced disease and align with earlier stages rather than Stage IV.