National Dental Examining Board of Canada (NDEB) Practice Exam

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Master your National Dental Examining Board of Canada (NDEB) exams with our comprehensive practice guide. Achieve excellence in your dental certification with expertly crafted questions and detailed explanations.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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For a Class I amalgam restoration, the occlusal cavosurface margin should be:

45 degrees
60 degrees
90 degrees
Beveled

The correct answer is: 90 degrees

For a Class I amalgam restoration, the occlusal cavosurface margin should be 90 degrees. This means that the cavity preparation should have a sharp and right angle with the rest of the tooth structure. A 45 degree margin would be too steep and could potentially weaken the structural integrity of the tooth, while a 60 degree margin would be less steep but still not ideal. Option D of having a beveled margin is also incorrect because beveling creates a sloped surface rather than a sharp angle, which can be a weak point for the restoration. The angle at the cavosurface margin is important for providing proper retention and resistance against occlusal forces, and a 90 degree margin is the most optimal for achieving this.