This case report is the fourth in a series that illustrates the application of the BSP implementation plan for diagnosing periodontitis patients according to the 2017 classification. It demonstrates the diagnostic approach and disease classification for a previously treated patient who presented with a diagnosis of unstable generalised periodontitis; stage IV, grade C. We describe a case of a 49-year-old patient who attended with a history of periodontal treatment over several years. Following a full periodontal assessment, the patient was diagnosed with 'generalised periodontitis; stage IV, grade C; currently unstable'. This case report presents an example of how to classify and diagnose a patient using the 2017 classification system and highlights challenges with the application of the new classification in patients with a previous history of periodontal therapy.
Keywords: Demonstrates the diagnostic approach and disease classification for a previously treated patient; Highlights challenges with the application of the new classification in patients with a previous history of periodontal therapy.; Illustrates the diagnosis and classification of periodontitis according to the 2017 classification system as recommended in the British Society of Periodontology (BSP) implementation plan.; grade C.; who presented with a diagnosis of unstable generalised periodontitis stage IV.