US 11,628,042 B1Granted

Endodontic instrument with enlarged chip space and reduced torque strength

OwnerWilliam B. Johnsoninventor

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Abstract

An endodontic instrument of this disclosure has less torque strength but greater flexibility and enlarged chip space compared to the prior art. In embodiments. only two flutes are spiraled about the instrument's length L to form two non-landed cutting edges between D2 and D16, the cutting edges merging to form a land at about D1. The tip end is rounded. The helical angle α increases from the handle end toward the tip end, a number of spirals per unit length being at least two times greater toward the tip end than toward the handle end, a cross-section of the length L consisting of two convex portions intersecting at each cutting edge or a wave-shape having one concave portion and one convex portion intersecting at each cutting edge, the cross-section occupying less total area than would a same size endodontic instrument having a triangular cross-section and providing greater chip space.

Claims6

Dependent claims

An endodontic instrument comprising:

a handle end;
a tip end;
a tapered shaft having a cutting length L extending 16 mm and having diameters D0 to D16, where D0 is the diameter at the tip end and D16 is the diameter at the handle end;
only two flutes spiraled about the length L at a helical angle α along the entire length L to form two cutting edges, the two cutting edges being non-landed between D2 and D16 and merging after D1 to form a land, the two cutting edges further forming a shovel blade beginning at D2 and ending at the tip end, the shovel blade having curved sides and the tip end being an end of the shovel blade and rounded;
the helical angle α increasing from the handle end toward the tip end, a number of spirals per unit length increasing toward D0, the number of spirals per unit length being greater between D0 and D5 than the number of spirals per unit length between D11 and D16;
a cross-section of the tapered shaft selected at each diameter D0 to D16 occupying less total area than 1.3 (Di/2)2, where i is an integer between 0 and 16;
wherein the cross-section lies in a plane orthogonal to the longitudinal axis of the endodontic instrument and contains a corresponding one of the diameters D0 to D16 and having a circle of rotation having a diameter, wherein the two cutting edges lie on the diameter of the circle of rotation;
the cross-section of the tapered shaft from D2 to D16 is asymmetrical wave-shape, the asymmetrical wave shape consisting of two waves opposing one another and intersecting at each cutting edge, each of the two waves having one concave portion and one convex portion, the one concave portion being shorter than the one convex portion.

5 more elements

A method for reducing instrument breakage while shaping a root canal during an endodontic procedure, the method comprising:

providing an endodontic instrument in an ISO 3630-1 size range of 10 to 35, the endodontic instrument including:
a handle end;
a tip end;
a tapered shaft having a cutting length L extending 16 mm and having diameters D0 to D16, where D0 is the diameter at the tip end and D16 is the diameter at the handle end;
only two flutes spiraled about the length L at a helical angle α along the entire length L to form two cutting edges, the two cutting edges being non-landed between D2 and D16 and merging after D1 to form a land, the two cutting edges further forming a shovel blade beginning at D2 and ending at the tip end, the shovel she blade having curved sides and the tip end being an end of the shovel blade and rounded;
the helical angle α increasing from the handle end toward the tip end, a number of spirals per unit length increasing toward D0, the number of spirals per unit length being greater between D0 and D5 than the number of spirals per unit length between D11 and D16;
a cross-section of the tapered shaft selected at each diameter D0 to D16 occupying less total area than 1.3 (Di/2)2, where i is an integer between 0 and 16;
wherein the cross-section lies in a plane orthogonal to the longitudinal axis of the endodontic instrument and contains a corresponding one of the diameters D0 to D16 and having a circle of rotation having a diameter, wherein the two cutting edges lie on the diameter of the circle of rotation;
wherein, the cross-section of the tapered shaft from D2 to D16 is asymmetrical wave-shape, the asymmetrical wave shape consisting of two waves opposing one another and intersecting at each cutting edge, each of the two waves having one concave portion and one convex portion, the one concave portion being shorter than the one convex portion.

6 more elements

Dependencies are inferred from the claim text.