Increasing the number of blades on a carbide bur produces which effect?

Correct answer: B. A smoother finished surface with reduced cutting efficiency

• A. Cutting efficiency cannot rise alongside blade number; the relationship is inverse.
• B. CORRECT. There is a direct trade-off. MORE blades means each blade takes a smaller bite, so the surface left behind is SMOOTHER — but the same geometry means less material is removed per revolution, so cutting efficiency FALLS. This is why finishing burs carry 12, 16 or 30 blades while cutting burs carry 6 or 8.
• C. Blade number is one of the principal determinants of both properties.
• D. More blades give a smoother, not rougher, surface.

Note: Same principle in diamonds: coarse grit cuts fast and leaves a rough surface; fine and extra-fine grits cut slowly and finish smoothly. Cut with coarse, finish with fine.