**Question:** Most common form of disinfection of alginate impression material is

A. Chlorhexidine
B. Povidone-iodine
C. Ethanol
D. Sodium hypochlorite

**Correct Answer:** D. Sodium hypochlorite

**Core Concept:**
Alginate impression materials are a type of dental impression material used for capturing the oral cavity's shape and detail during the fabrication of dental restorations. To prevent the transmission of cross-infection between patients, it is essential to disinfect these materials before re-use.

**Why the Correct Answer is Right:**
Sodium hypochlorite (Option D) is a common disinfectant agent due to its broad-spectrum antimicrobial properties. It works by breaking down the cellular structures, disrupting cellular functions, and causing cell death. Its concentration should be around 5% to ensure effective disinfection without damaging the impression material.

**Why Each Wrong Option is Incorrect:**

A. Chlorhexidine (Option A) is a popular dental antiseptic, but it is usually used as a mouthwash or topical gel, not for disinfecting impression materials. Chlorhexidine is not as effective on non-polar surfaces like alginate impression materials.

B. Povidone-iodine (Option B) is a broad-spectrum antimicrobial agent, but its use is discouraged for disinfecting impression materials due to its hydrophilic nature. It tends to bind to the hydrophobic alginate molecules, affecting the material's properties and making it unsuitable for dental use.

C. Ethanol (Option C) is an effective antiseptic, but its concentration for disinfecting impression materials should be 70-90%, which can damage the alginate material and compromise its quality. Lower concentrations may not be effective against certain microorganisms.

**Clinical Pearl:**
To minimize cross-infection risks in dental settings, it is crucial to use the correct disinfectant agent for dental impression materials. In this case, sodium hypochlorite (Option D) is the suitable choice for disinfecting alginate impression materials, ensuring patient safety while maintaining the material's quality.