**Question:** Which of the following oral structures are not affected in Leprosy?

**Core Concept:** Leprosy is a chronic infectious disease caused by Mycobacterium leprae and M. leprae. It primarily affects the skin, peripheral nerves, eyes, and respiratory system. The disease has a characteristic presentation based on the immune response to the bacteria.

**Why the Correct Answer is Right:** Leprosy primarily affects the skin, peripheral nerves, eyes, and respiratory system due to the immune response to M. leprae and M. leprae. The oral structures, such as the teeth, salivary glands, and oral mucous membrane, are only minimally affected in leprosy. The immune response targets the bacteria and its effects, leaving the oral structures relatively unaffected.

**Why Each Wrong Option is Incorrect:**

A. Teeth: Although not directly affected by the bacteria, M. leprae can cause osteomyelitis (bone infection) and endodontic (root canal) infections in teeth, but these are not considered part of the primary oral manifestations.

B. Salivary glands: Leprosy can cause hypofunction of the salivary glands (xerostomia) due to nerve damage, but the salivary glands themselves are not directly involved.

C. Oral mucous membrane: The oral mucous membrane is not directly affected by the bacteria and the immune response.

D. Oral lesions: Leprosy can affect the oral mucous membrane but not as a primary manifestation.

**Clinical Pearl:** The immune response to M. leprae and M. leprae primarily targets the skin, nerves, eyes, and respiratory system. While M. leprae can cause dental and salivary gland complications, the primary oral manifestation of leprosy is oral lesions, which are not considered in this question.

**Correct Answer:** C. Oral mucous membrane

**Core Concept:** Oral mucous membrane is not directly affected by the bacteria and the immune response in leprosy. The primary focus of the disease is on the skin, nerves, eyes, and respiratory system. Although M. leprae can cause oral lesions, dental, and salivary gland complications, the question specifically asks about the primary oral structures that are not affected by leprosy.