**Question:** Investigation using dye to find out stone in salivary gland

**Core Concept:** Salivary gland stones, also known as sialolithiasis, are solid masses formed within the salivary glands, typically in the parotid gland. These stones are composed of salivary components and can cause local inflammation, pain, and swelling.

**Why the Correct Answer is Right:**

The correct answer, **Option D**, refers to sialography, a radiographic technique used to locate and visualize salivary gland stones. During sialography, a contrast medium (dye) is injected into the salivary gland duct, and X-rays are taken to visualize the stone and surrounding structures. This method helps in diagnosing sialolithiasis accurately and planning surgical interventions, if required.

**Why Each Wrong Option is Incorrect:**

**Option A** is incorrect as it refers to sialendoscopy, which is a minimally invasive procedure used to visualize and diagnose salivary gland disorders. While it can be used to identify stone locations, it is not an investigation technique itself.

**Option B** is incorrect as it refers to sialendonography, an incorrect term. Sialendoscopy and sialography are more suitable options for diagnosing salivary gland stones.

**Option C** is incorrect as it refers to sialendoscopy-guided sialolith removal, which is a treatment procedure rather than an investigation technique for diagnosing salivary gland stones.

**Clinical Pearl / High-Yield Fact:**

Salivary gland stones can be diagnosed using various techniques, such as sialography, sialendoscopy, and sialendonography. However, sialography is a common imaging technique that involves injecting a contrast medium into the salivary gland duct to visualize the stone and surrounding structures. This helps in identifying the stone location and planning the appropriate treatment strategy.

**Correct Answer:**

**Option D** refers to sialography, which uses a contrast medium to visualize salivary gland stones and surrounding structures during X-ray examination. Sialography is essential for accurate diagnosis and treatment planning of salivary gland stones.