**Question:** Recent classification of periodontal disease organized by American Academy of Periodontology was introduced in the year:

A. 1985
B. 1999
C. 2000
D. 2017

**Core Concept:** Periodontal diseases are a group of inflammatory conditions affecting the supporting structures of the teeth, primarily caused by bacterial infections. The American Academy of Periodontology (AAP) is a professional organization that maintains guidelines and classifies periodontal diseases.

**Why the Correct Answer is Right:** The correct answer is D. 2017, because the AAP published the 9th Classification of Periodontal Diseases and Conditions in 2017. This classification system aims to standardize terminology and provide a comprehensive framework for describing and understanding periodontal diseases.

**Why Each Wrong Option is Incorrect:**

A. 1985: The 8th Classification of Periodontal Diseases was published in 1985, making it an incorrect answer.
B. 1999: The 9th Classification was published in 2017, rendering this option incorrect.
C. 2000: The 9th Classification of Periodontal Diseases was published in 2017, making this option incorrect as well.

**Clinical Pearl:** The AAP's Classification of Periodontal Diseases and Conditions is essential for dental professionals to understand as it helps in accurate diagnosis, treatment planning, and patient management.

**Correct Answer:** D. 2017