Patent ID: 8852222

Claim:
A surgical bur, said bur including: an elongated shaft having opposed proximal and distal ends; a coupling feature associated with the proximal end of said shaft, the coupling featured shaped to engage a drive unit of a surgical handpiece so that the handpiece can rotate said shaft; a bur head attached to the distal end of said shaft, the bur head having: a body with a distal end tip; a longitudinal axis that extends through the body including through the distal end tip; and a plurality of flutes that emerge from said body, wherein each said flute has a rake surface and a clearance surface that meet to define a cutting edge that extends radially beyond said shaft wherein: a single pair of first flutes that are symmetric to each other around the body distal end tip and that emerge from said bur head body distal end tip so as to have cutting edges that extend proximally from a distal position that is located adjacent said bur head body distal end tip and wherein said flutes forming the pair of first flutes are separated from each other by opposed arcuate sections of said bur head body; a single pair of second flutes that are symmetric to each other around said bur head body distal end tip, wherein said flutes forming the pair of second flutes emerge from separate arcuate sections of said bur head body; two pairs of third flutes, the pairs of the third flutes positioned so that: said flutes forming each pair of third flutes emerge from separate arcuate sections of said bur head body; one of said flute pairs of said third flutes are symmetric around said bur head body distal end tip; and each third flute is located between one of the first flutes and one of the second flutes; first chamfer surfaces extend proximally from adjacent said bur head body distal end tip, each said first chamfer surface forming a distal end face of one of the second flutes and the third flutes adjacent the second flute so that the each second flute has cutting edge that extends proximally from a position along the bur head that is spaced proximal to the distal end tip, and the first chamfer surfaces are at a first chamfer angle relative to the bur head longitudinal axis; and a second chamfer surface extends over each third flute, the second chamfer surfaces extending proximally relative to the first chamfer surfaces and being at a second chamfer angle relative to the bur head longitudinal axis, the second chamfer angle being less than the first chamfer angle so that each third flute has a cutting edge that extends distally from a position along the bur head that is spaced proximal to the position from which the cutting edges of the second flutes extend proximally.