What material is used in a vitality test to stimulate a tooth's reaction to cold?

In a vitality test, ethyl chloride is used as it is a cold stimulus that effectively elicits a response from the tooth being tested. The purpose of this test is to determine the tooth's vitality, or whether it is alive and responsive. Ethyl chloride rapidly evaporates and creates a cooling effect when applied to the tooth or surrounding tissue, allowing dental professionals to assess pulp vitality through the patient’s reaction, with a positive response indicating that the pulp is still healthy.

Other materials listed, such as alginate, are primarily used for making impressions; gutta-percha is mainly utilized in endodontic treatments, particularly for root canal fillings; and sodium hypochlorite is used for irrigation and disinfection in root canal therapy. None of these serve the purpose of stimulating a tooth's reaction to cold, which is specific to ethyl chloride in the context of a vitality test.