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
In non zinc containing dental amalgam alloy, the percentage of zinc present is 
Select and explain. 
A. Less than 0.02%, B. Less than 0.1%, C. Less than 0.01%, D. None of the above
C: Less than 0.01%
Answer: C: Less than 0.01% 
Explanation: The ANSI/ADA specification also includes a notation about the presence of zinc in amalgam alloys, with more than 0.01% zinc classified as zinc containing and those with less than 0.01% as non-zinc alloys. Zinc has been included in amalgam alloys as an aid in manufacturing; it helps produce clean, sound castings of the ingots used for producing lathe-cut alloys. The presence of contamination within the amalgam must be avoided because it can degrade the integrity of the restoration.