Carbide: which cut for which task?

Carbide instruments cut rather than grind. How they cut is determined by the toothing: the number, shape and course of the cutting edges determine removal rate, smooth running and surface finish. In the clinic, a few proven toothings are sufficient. In the laboratory, where plaster, resins and alloys are worked side by side, each material needs its own.

Basic rule: chip space versus surface

• Coarse toothing with few cutting edges and large chip space removes material quickly and clogs less with soft materials.
• Fine toothing with many cutting edges removes less material and leaves smoother surfaces.
• Cross toothing breaks the chip into short pieces. The instrument runs more smoothly, does not catch and remains easier to control.

Read more about the interplay of toothing and speed in Understanding toothing and speed.

Clinic: standard toothing as usual

For preparation, removal of old fillings and trimming of metal and resin, the carbide burs work with the proven standard toothing, with FG shank for the turbine, RA for the contra-angle and HP for the handpiece:

• Straight toothing, for example on the round bur H1 for caries removal and cavity preparation
• Spiral toothing on the fissure burs H21 and H23, such as cylinder and cone, for an even cut along the cutting edge
• Spiral toothing with crosscut on H31 and H33: the crosscut breaks the chip, making it easier to remove old fillings

Laboratory: toothing according to material

The tungsten carbide burs for the laboratory carry an identification letter for the toothing, for example H129E or H129EF. Each toothing is matched to specific materials: