This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Vitality test has to be done over a PFM crown, which is the best test to be done in order to check the vitality: 
Select and explain. 
A. EPT., B. Cold test., C. Cavity test., D. All of the above.
B: Cold test.
Answer: B: Cold test. 
Explanation: For PFM → EPT is contraindicated, instead cold test With CO2 snow/“TRIGIDENT “is a  test of Choice. (Temperature of dry ice/CO2 snow is–78ºC) .