Dental Which of the following statements about an amalgam tooth/cavity preparation is true? A The enamel cavosurface margin angle must be 90 degrees. B The cavosurface margin should provide for a 90- degree amalgam margin. C All prepared walls should converge externally. D Retention form for Class Vs can be placed at the DEJ. 💡 Explanation Which of the following statements about an amalgam tooth/cavity preparation is true? ✓ Correct Answer: B. The cavosurface margin should provide for a 90- degree amalgam margin.