Periodontal diagnostic tests include clinical methods, radiographic methods, microbial analysis, and host response analysis. Clinical methods include gingival bleeding, periodontal probing, tooth mobility, gingival temperature, and halitosis. Bleeding on probing and increased gingival temperature can indicate inflammation but are not reliable predictors of future attachment loss. Periodontal probing is important but multiple factors can affect accuracy. Digital radiography and subtraction radiography allow for enhanced detection and quantification of alveolar bone loss compared to conventional radiographs.