**Core Concept**
Acute Necrotizing Ulcerative Gingivitis (ANUG) is a severe infection of the gums characterized by necrosis and ulceration of the gingival tissue. Effective treatment modalities for ANUG focus on eliminating the infection, alleviating symptoms, and promoting healing.

**Why the Correct Answer is Right**
The primary treatment for ANUG involves addressing the underlying bacterial infection. This is typically achieved through a combination of good oral hygiene practices, such as regular brushing and flossing, and the use of antimicrobial agents like antibiotics and chlorhexidine mouthwash. Additionally, pain management with analgesics and anti-inflammatory medications can help alleviate symptoms. In severe cases, surgical debridement may be necessary to remove dead tissue and promote healing.

**Why Each Wrong Option is Incorrect**
**Option A:** While smoking is a significant risk factor for ANUG, it is not a treatment modality.
**Option B:** Scaling and root planing are essential for treating periodontal diseases, but they are not the primary treatment for ANUG.
**Option C:** Antibiotics and antimicrobial mouthwashes are crucial in treating ANUG, but this option is too vague and does not provide a specific treatment modality.

**Clinical Pearl / High-Yield Fact**
It's essential to note that ANUG is often associated with poor oral hygiene, smoking, and stress. Patients with a history of ANUG should be advised to practice excellent oral hygiene, avoid smoking, and manage stress to reduce the risk of recurrence.

**Correct Answer: D. Smoking is a risk factor for ANUG but not a treatment modality.**