What effect does a greater number of cutting blades on carbide burs at low speed have?

Choosing a cutting instrument with a greater number of cutting blades on carbide burs at low speeds results in less efficient cutting and a smoother surface. This is because the increased number of cutting edges distributes the cutting action more evenly across the surface being worked on, which minimizes the depth of cut per blade engagement. As a result, each blade removes smaller amounts of material, leading to a smoother finish since the cumulative cutting action is finer and less aggressive.

Additionally, at low speeds, the reduced force exerted on the material further encourages the creation of a smoother surface, as blades glide rather than aggressively cut into the substrate. Conversely, fewer blades tend to remove larger chips and may generate a rougher surface due to the more aggressive cutting action associated with each blade. Thus, the correct answer captures the balance between efficiency of cut and surface finish resulting from high blade counts at lower speeds.