Edge Angle: The angle formed at the cutting edge of a
bur blade. Increasing the edge angle reinforces the cutting edge, which
helps to reduce the likelihood of blade fracture during use.
Reinforcement: A larger edge angle provides more
material at the cutting edge, enhancing its strength and durability.
Carbide vs. Steel Burs
Carbide Burs:
Hardness and Wear Resistance: Carbide burs are
known for their higher hardness and wear resistance compared to steel
burs. This makes them suitable for cutting through hard dental tissues.
Brittleness: However, carbide burs are more brittle
than steel burs, which means they are more prone to fracture if not
designed properly.
Edge Angles: To minimize the risk of fractures,
carbide burs require greater edge angles. This design consideration is
crucial for maintaining the integrity of the bur during clinical
procedures.
Interdependence of Angles
Three Angles: The cutting edge of a bur is defined by
three angles: the edge angle, the clearance angle, and the rake angle. These
angles cannot be varied independently of each other.
Clearance Angle: An increase in the clearance angle
(the angle between the cutting edge and the surface being cut) results
in a decrease in the edge angle. This relationship is important for
optimizing cutting efficiency and minimizing wear on the bur.
