What clinical finding is most indicative of chronic periodontal disease?

The presence of gingival bleeding on probing is a significant clinical finding indicative of chronic periodontal disease. This symptom reflects inflammatory changes in the periodontal tissues, which are characteristic of chronic conditions. When probing reveals bleeding, it signifies that the gingiva is inflamed, often due to the presence of plaque and calculus, leading to periodontal tissue breakdown. Chronic periodontal disease is often marked by a chronic inflammatory response, and bleeding on probing demonstrates the active state of inflammation in the periodontal tissues.

In contrast, while pocket depths greater than 4 mm and localized tooth mobility can also be associated with periodontal disease, they are not as specifically indicative of chronic inflammation as gingival bleeding. Deep calculus may contribute to the disease but is not a direct indicator of the severity or chronicity of the inflammation. Therefore, bleeding on probing is a more reliable sign of the active disease process associated with chronic periodontal disease.