## **Core Concept**
The Ellis and Dewey classification is used to categorize dental injuries, specifically those affecting the teeth. This classification helps in the diagnosis and treatment planning of dental traumas. It primarily focuses on the type of injury to the tooth.

## **Why the Correct Answer is Right**
The correct classification for displacement of a tooth without fracture of the crown or root, according to Ellis and Dewey, is **Class 3**. This classification involves displacement of the tooth in a labial, lingual, mesial, or distal direction without any fracture of the crown or root. This type of injury can lead to damage to the periodontal ligament and sometimes the pulp.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not correspond to the description provided for Class 3 injuries.
- **Option B:** This could potentially refer to another classification but does not match the description of a tooth displacement without fracture.
- **Option D:** This option is incorrect because it does not accurately represent the classification for displacement without fracture according to Ellis and Dewey.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that dental trauma classifications help guide treatment and prognosis. For Ellis and Dewey Class 3 injuries, follow-up is crucial to monitor for potential pulp necrosis or other complications.

## **Correct Answer:** . **Class 3**