**Question:** Best medium to transport an avulsed tooth, which is not to be reimplanted immediately:

A. Milk
B. Saline solution
C. Plain water
D. Plasma

**Correct Answer:** B. Saline solution

**Core Concept:** When dealing with avulsed teeth, the primary goal is to maintain the tooth's vitality until it can be reimplanted or treated by a dentist. Transportation media should be chosen based on their ability to preserve tooth tissue and inhibit bacterial growth.

**Why the Correct Answer is Right:** Saline solution (sodium chloride solution) is the best option among these choices because:

1. **Saline solution maintains osmotic balance:** Avulsed teeth require a medium with the same osmotic pressure as the oral cavity to prevent cell dehydration and tissue damage. Saline provides this balance, helping to preserve the tooth's vitality.
2. **Saline solution inhibits bacterial growth:** It has a lower pH and osmolarity than water, which reduces the chances of bacterial growth within the tooth socket, minimizing infection risk during transportation.

**Why Each Wrong Option is Incorrect:**

A. Plain water:
- **Water lacks osmotic balance:** Water's osmolarity is different from that of the oral cavity, leading to cell dehydration and tissue damage.
- **Water promotes bacterial growth:** Water provides a hospitable environment for bacteria, increasing the risk of infection during transportation.

C. Plain water: Same reasons as option A apply here, reinforcing the importance of choosing a medium with proper osmotic balance and inhibiting bacterial growth.

D. Plasma:
- **Plasma is a complex solution:** It contains blood components, making it unsuitable for transporting an avulsed tooth due to its complexity and potential contamination risks.

**Clinical Pearl:** An avulsed tooth's survival depends on prompt treatment, ideally within 30 minutes of the injury. The choice of transport medium significantly impacts the tooth's viability, making saline solution the optimal option among the given choices.