## **Core Concept**
Tooth sensitivity testing is crucial in assessing the vitality of traumatized teeth. Various methods can be employed, including thermal tests, electrical tests, and mechanical tests. In young permanent teeth, thermal tests are particularly useful.

## **Why the Correct Answer is Right**
The use of carbon dioxide snow for sensitivity testing is beneficial because it provides a rapid and significant thermal change. Carbon dioxide snow can reach temperatures as low as **-78.5°C**, making it an effective agent for stimulating a response in teeth. This method is especially suitable for young permanent teeth due to its non-invasive nature and the quick results it provides.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because the temperature mentioned does not correspond with the known properties of carbon dioxide snow.
- **Option B:** This option suggests a temperature that is not as low as what carbon dioxide snow can achieve.
- **Option D:** This option implies a higher temperature than what is associated with the use of carbon dioxide snow for dental sensitivity testing.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that carbon dioxide snow is a valuable tool in dental diagnostics, particularly for assessing tooth vitality in cases of trauma. Its use can help in determining the need for further intervention. A classic clinical correlation is that a tooth's response to cold stimuli can indicate its vitality, with non-responsive teeth potentially being necrotic or in need of root canal therapy.

## **Correct Answer:** . -78.5°C.