Autografting tool with enhanced flute profile and methods of use
Tools and methods for expanding a precursor hole in a host material to receive a fixture. The precursor hole is enlarged by a rotary tool having helical flutes and interposed lands. The flutes have a negative rake angle. The lands each have a working edge that cuts the host material when the tool is rotated in a cutting direction, and that condenses the host material when the tool is rotated in a densifying direction. The body of the rotary tool has a stopper section that plugs the hole when a certain depth is reached. When the tool is used with a copious wash of irrigating fluid at or below the necessary depth, hydraulic pressure builds inside the precursor hole. The hydraulic pressure can be advantageously exploited in cutting mode to autograft a slurry of host material particles into the sidewalls of the hole and create an incipient densifying crust.
1. A rotary osteotome operable in a cutting direction and a reverse densifying direction, comprising:
a shank establishing a longitudinal axis of rotation for the cutting and reverse densifying directions,
a body extending from said shank, said body having an apical end remote from said shank, a plurality of helically spiraling flutes disposed about said body, each said flute having a cutting face on one side thereof defining a rake angle and a densifying face on the other side thereof defining a heel-side angle, for each said densifying face the associated said heel-side angle is a positive angle measured in the cutting direction, said flutes having an axial length and radial depth, a stopper section of said body disposed between said flutes and said shank, a land formed between each adjacent pair of flutes, each said land having a working edge along said cutting face of the one adjacent said flute, said working edge helically twisting about said body,
wherein the improvement comprises:
for each said cutting face at least a portion of the associated said rake angle is a negative rake angle measured in the cuffing direction.
2. The rotary osteotome of claim 1 , wherein said flutes have a regressive depth measuring deepest adjacent said apical end and shallowest adjacent said stopper section.
3. The rotary osteotome of claim 1 , said negative rake angle fluctuates along the length of each said flute with a total variance of less than 30°.
4. The rotary osteotome of claim 1 , wherein said negative rake angle fluctuates along the length of each said flute with a total variance of greater than 30°.
5. The rotary osteotome of claim 1 , wherein said negative rake angle changes along the length of each said flute in a progressive manner.
6. The rotary osteotome of claim 1 , wherein said negative rake angle changes along the length of each said flute in a regressive manner.
7. The rotary osteotome of claim 1 , wherein said heel-side angle is generally constant along the length of each said flute.
8. The rotary osteotome of claim 1 , wherein said heel-side angle fluctuates along the length of said flutes with a total variance of less than 30°.
9. The rotary osteotome of claim 8 , wherein said working edges wind about said body in a direction that turns away from a non-cutting direction as said conically tapered profile decreases in diameter.
10. The rotary osteotome of claim 1 , wherein said body has a conically tapered profile decreasing from a maximum diameter adjacent said shank to a minimum diameter adjacent said apical end.