Endodontic instruments displaying compressibility

Abstract

Endodontic instruments are used to clean and enlarge the endodontic cavity space (ECS), also known as the root canal system, of a human tooth. This document describes novel endodontic instruments that are radially compressible, and methods for their use. Some embodiments include a shank and a body with a working surface. At least a portion of the working surface may define a center of mass path that spirals. The center of mass of a transverse cross-section of the working surface at the shank end can be offset from the axis of rotation of the instrument.

What is claimed is: 
     
         1 . An endodontic instrument for preparing an endodontic cavity space, the endodontic instrument comprising:
 a shank configured for attachment to a motor to drive the endodontic instrument about a first axis; and   a body extending from the shank by a length, the body being solid and having a working surface between: (i) a shank end portion where the working surface and the shank meet and (ii) a tip end portion where the working surface meets a tip of the endodontic instrument, the working surface including multiple edges, at least a portion of the working surface being tapered such that the tip end portion has a diameter that is less than a diameter of the shank end portion,   the working surface comprising a plurality of transverse cross-sections, each transverse cross-section having a center of mass and multiple sides, the working surface having a center of mass path defined by the centers of mass of the plurality of transverse cross-sections of the body,   wherein the endodontic instrument is configured to be radially compressible between: (i) an unconstrained configuration in which at least a portion of the center of mass path between the tip end portion and the shank end portion is offset from the first axis and spirals around the first axis along a length of the first axis, and (ii) a radially constrained configuration in which the portion of the center of mass path is more aligned with the first axis than in the unconstrained configuration, and   wherein a cutting profile of the endodontic instrument is radially smaller in the radially constrained configuration than in the unconstrained configuration, and wherein the cutting profile of the endodontic instrument radially expands during preparing the endodontic cavity space such that the endodontic cavity space is prepared by rotating the endodontic instrument singularly in lieu of rotating a series of multiple endodontic instruments of increasing sizes, and   wherein, after the endodontic cavity space is prepared by rotating the endodontic instrument singularly in lieu of rotating a series of multiple endodontic instruments of increasing sizes, the endodontic cavity space is sized for filling.   
     
     
         2 . The endodontic instrument of  claim 1 , wherein the body is configured such that when the endodontic instrument is driven within the endodontic cavity space about the first axis, at each transverse section of at least a portion of the length of the body, one or more edges of the multiple edges are out of contact with a wall of the endodontic cavity space while the endodontic instrument is in the unconstrained configuration. 
     
     
         3 . The endodontic instrument of  claim 2 , wherein the working surface comprises a reversed helix. 
     
     
         4 . The endodontic instrument of  claim 2 , wherein the portion of the center of mass path that spirals around the first axis extends from the tip end portion to the shank end portion. 
     
     
         5 . The endodontic instrument of  claim 4 , wherein the plurality of transverse cross-sections includes a transverse cross-section that is quadrilateral. 
     
     
         6 . The endodontic instrument of  claim 5 , wherein each of the plurality of transverse cross-sections is quadrilateral. 
     
     
         7 . The endodontic instrument of  claim 6 , wherein a ratio of lengths of sides of the quadrilateral remain constant along the length of the body. 
     
     
         8 . The endodontic instrument of  claim 7 , wherein the plurality of transverse cross-sections includes a transverse cross-section at the tip end portion that has a center of mass that coincides with the first axis. 
     
     
         9 . The endodontic instrument of  claim 1 , wherein the plurality of transverse cross-sections includes a transverse cross-section that is triangular. 
     
     
         10 . The endodontic instrument of  claim 1 , wherein the plurality of transverse cross-sections includes a transverse cross-section that is asymmetrical. 
     
     
         11 . The endodontic instrument of  claim 1 , wherein the plurality of transverse cross-sections includes a first transverse cross-section and a second transverse cross-section, wherein the first transverse cross-section has a first geometry, and wherein the second transverse cross-section has a second geometry different from the first geometry. 
     
     
         12 . The endodontic instrument of  claim 11 , wherein each transverse cross-section between the first transverse cross-section and the second transverse cross-section has a gradually changing geometry with respect to each other. 
     
     
         13 . The endodontic instrument of  claim 1 , wherein the body comprises nickel-titanium. 
     
     
         14 . The endodontic instrument of  claim 13 , wherein the plurality of transverse cross-sections includes a first transverse cross-section and a second transverse cross-section, wherein a center of mass of the first transverse cross-section is spaced apart from the first axis by a first distance, wherein a center of mass of the second transverse cross-section is spaced apart from the first axis by a second distance, and wherein the first distance is greater than the second distance. 
     
     
         15 . The endodontic instrument of  claim 1 , wherein each transverse cross-section of the body is defined by a polygonal shape, and wherein a ratio of lengths of sides of the polygonal shape vary along the length of the body. 
     
     
         16 . The endodontic instrument of  claim 15 , wherein the plurality of transverse cross-sections includes a transverse cross-section at the tip end portion that has a center of mass that coincides with the first axis.