National Dental Examining Board of Canada (NDEB) Practice Exam

What is the reason for adding copper to dental amalgam?

1. To induce a silver-mercury phase

2. To reduce tin-mercury phase and increase compressive strength

3. To enhance aesthetic appeal

4. None of the above

The correct answer is: To reduce tin-mercury phase and increase compressive strength

Dental amalgam is a commonly used material for filling cavities in teeth. It is made up of a mixture of silver, tin, copper, and other metals. The addition of copper to dental amalgam serves to reduce the formation of a weaker, tin-mercury phase, and instead, increase the formation of a stronger, silver-mercury phase. This results in improved compressive strength of the amalgam, making it more durable and less susceptible to fracture. Adding copper does not directly contribute to the aesthetics of the amalgam, thus option A and C are incorrect. Option D, saying that there is no reason for adding copper, is also incorrect as explained above.