The histological section of tooth under orthodontic force representing an avascular area in the periodontal ligament is often referred as
**Core Concept**
The underlying principle being tested is the histological response of the periodontal ligament to orthodontic forces, specifically the areas undergoing necrosis due to compression. This phenomenon is crucial in understanding tooth movement. The periodontal ligament plays a vital role in anchoring the tooth to the surrounding bone.
**Why the Correct Answer is Right**
The correct term for the avascular area in the periodontal ligament under orthodontic force is related to the region's hyalinization due to compression. This area is characterized by the absence of blood vessels, hence avascular, and is a direct result of the pressure exerted by the orthodontic appliance. The hyalinized tissue is less cellular and has fewer blood vessels.
**Why Each Wrong Option is Incorrect**
**Option A:** This is not the term used to describe the avascular area in the periodontal ligament.
**Option B:** Similarly, this option does not accurately describe the histological change in the periodontal ligament under orthodontic force.
**Option D:** This option is also incorrect as it does not represent the avascular, compressed area in the periodontal ligament.
**Clinical Pearl / High-Yield Fact**
The key point to remember is that orthodontic forces can cause areas of compression and tension in the periodontal ligament, leading to different histological changes. Understanding these changes is crucial for effective and safe orthodontic treatment.
**Correct Answer:** C. Hyalinized zone.