Ace the California RDA Written Exam 2026 – Drill, Fill, and Thrill Your Way to Success!

The pulpal floor is the correct answer because it refers to the bottom surface of the cavity preparation where the base material is placed.

Option B, marginal ridge, is incorrect because it refers to the raised edges of the preparation, not the bottom surface where the base is placed.

Option C, cavity wall, is also incorrect because it refers to the sides of the preparation, not the bottom surface.

Option D, enamel surface, is incorrect because it refers to the outer layer of the tooth, not the specific location within the preparation.