A patient has severe attachment loss, tooth migration/mobility, deep bone loss, and rapid progression at a young age. Using the 2017 periodontitis classification, this is best described as:

Correct answer: A. Stage IV, Grade C

• A. Correct. Stage IV reflects advanced disease with masticatory dysfunction/tooth loss; Grade C denotes rapid progression (often disproportionate to risk factors).
• B. Incorrect. Stage I/Grade A is the earliest, slowest category — opposite of this presentation.
• C. Incorrect. Stage II/Grade B is moderate disease with moderate progression.
• D. Incorrect. Gingivitis has no attachment or bone loss.