## **Core Concept**
The question pertains to dental bleaching techniques, specifically focusing on "in-office" non-vital bleaching methods. Dental bleaching can be categorized based on the location (in-office vs. at-home), the type of tooth (vital vs. non-vital), and the technique used. Non-vital bleaching refers to the process of whitening teeth that are no longer alive, often due to root canal treatment.

## **Why the Correct Answer is Right**
The correct answer, **Walking Bleach**, is a technique used for non-vital teeth. It involves placing a mixture of hydrogen peroxide and a low concentration of bleach inside the tooth and sealing it for a period, typically a week, before removing and reapplying as needed. This method is specifically designed for non-vital teeth that have undergone root canal therapy and are discolored. The term "walking" refers to the periodic replacement of the bleaching agent.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and therefore cannot be considered a valid technique.
- **Option B:** Similarly, this option is blank and does not represent a recognized dental bleaching technique.
- **Option C:** This option is also blank, lacking any specific reference to a dental bleaching method.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **walking bleach** is specifically indicated for non-vital teeth, often those that have undergone root canal therapy. It's a highly effective method for addressing discoloration in such teeth. A classic clinical correlation is that this technique requires careful sealing of the tooth to prevent leakage of the bleaching agent and potential damage to the surrounding tissues.

## **Correct Answer:** . Walking Bleach