Comparing a plain-cut fissure bur with a cross-cut fissure bur, which statement is correct?

Correct answer: B. The cross-cut bur cuts more efficiently; the plain-cut bur leaves a smoother surface

• A. The cross-cut bur is the more efficient of the two but does not leave the smoother surface.
• B. CORRECT. CROSS-CUTS are transverse notches cut across the blades, breaking the continuous cutting edge into a series of small teeth. This fragments the material being removed and greatly increases CUTTING EFFICIENCY — but each notch leaves its own mark, so the surface is comparatively ROUGH. The plain-cut bur has an uninterrupted edge and leaves a SMOOTHER surface at the cost of speed.
• C. They differ markedly in both respects.
• D. This reverses both properties.

Note: This is the same efficiency-versus-finish trade-off as blade number and diamond grit. Bulk reduction calls for cross-cut; final wall refinement calls for plain-cut.