## **Core Concept**
The success of a replanted tooth depends on various factors, including the condition of the periodontal ligament, the storage medium used, and the extra-alveolar time. Tooth replantation involves the avulsion of a tooth, followed by its reinsertion into the alveolar socket.

## **Why the Correct Answer is Right**
The periodontal ligament (PDL) plays a crucial role in the healing and survival of a replanted tooth. When a tooth is avulsed, the PDL cells can be damaged or destroyed, leading to complications such as root resorption, ankylosis, or failure of the tooth to replant successfully. The PDL is essential for the regeneration of the attachment apparatus and for maintaining the health of the surrounding bone and gingiva.

## **Why Each Wrong Option is Incorrect**
* **Option A:** While infection can be a complication of tooth replantation, it is not the most common reason for failure.
* **Option B:** Trauma during replantation can cause damage but specifying it as most common reason is inaccurate.
* **Option C:** This option seems to pertain potentially to a procedural aspect or another factor not directly linked to the biological integration of the tooth.

## **Clinical Pearl / High-Yield Fact**
A key factor in the success of tooth replantation is the extra-alveolar time; the sooner the tooth is replanted, the better the chances of PDL cell survival and successful replantation. Immediate replantation or storage in a suitable medium like milk or saline can improve outcomes.

## **Correct Answer:** D. Root resorption due to damage to periodontal ligament.