Glossary

A super-elastic alloy (~56% nickel, ~44% titanium) used in most modern rotary files. Its shape-memory and flexibility allow instruments to navigate curved canals with less risk of transportation.

A proprietary NiTi alloy produced by a thermomechanical process that increases cyclic fatigue resistance compared to conventional NiTi while retaining cutting efficiency.

A post-manufacturing thermal process that gives files their characteristic gold color. It significantly improves flexibility and cyclic fatigue resistance by optimizing the martensitic phase transformation.

A proprietary thermomechanical process producing a visible blue titanium-oxide surface layer. Blue-treated files exhibit a controlled memory effect and superior cyclic fatigue resistance.

A heat-treated NiTi alloy that lacks conventional shape memory, allowing the file to be pre-curved before use. This significantly improves adaptation to canal anatomy and cyclic fatigue life.

An intermediate crystallographic phase between austenite and martensite in NiTi alloys. Files manufactured in the R-phase exhibit exceptional flexibility and resistance to cyclic fatigue.

A controlled-memory NiTi alloy developed by Coltene for the HyFlex product line. C.Wire files can be pre-bent and show high cyclic fatigue resistance due to their martensitic microstructure.

A heat-treated NiTi alloy used in TruNatomy instruments. It provides a slim file design with enhanced flexibility, allowing preservation of dentin during shaping.

A manufacturing method that uses electrical spark erosion instead of grinding to shape NiTi files. EDM produces a harder surface with micro-craters that improve cutting and fatigue resistance.

A shape-memory NiTi alloy used in the XP-endo Shaper. At body temperature it transforms from a straight martensitic form to an expanded austenitic shape, enabling adaptive canal contact.

A drive mode in which the file rotates 360 degrees in one direction without reversal. Most multi-file NiTi systems use continuous rotation, typically between 250-500 rpm depending on the manufacturer.

A drive mode that alternates between a larger counter-clockwise cutting angle and a smaller clockwise releasing angle. It reduces the risk of torsional failure and is used by single-file systems.

A proprietary drive mode (Kerr/SybronEndo) that automatically switches between continuous rotation and reciprocation based on the intra-canal load detected on the file.

A general term for drive programs that combine elements of continuous rotation and reciprocation, either within one revolution cycle or by switching modes adaptively during instrumentation.

The rate of increase in file diameter from tip to shaft, expressed as a percentage per millimeter. A .06 taper means the diameter increases 0.06 mm for each millimeter of length.

The diameter of the file at its tip (D0), measured in hundredths of a millimeter. A size 25 file has a tip diameter of 0.25 mm. Tip size determines the minimum apical preparation diameter.

Metal fatigue caused by repeated tension-compression cycles as a rotating file flexes around a canal curvature. It is the primary cause of unexpected file separation in curved canals.

The ability of a file to resist fracture when its tip locks in the canal while the shaft continues to rotate. Higher torsional resistance reduces the risk of tip-driven breakage.

A smooth, reproducible pathway from canal orifice to the apical foramen created before rotary shaping. It is typically established with hand K-files (#10-#15) or dedicated mechanical path files.

The distance from a coronal reference point to the apical constriction, defining how deep each instrument should reach. Accurate working length is critical to prevent under- or over-instrumentation.

An electronic device that measures impedance changes to determine the position of the apical foramen. Modern multi-frequency apex locators are accurate to within 0.5 mm in most clinical conditions.

A shaping strategy that instruments the coronal portion of the canal first, then progressively works toward the apex. It reduces coronal interference and improves irrigant penetration.

An undesirable deviation of the prepared canal away from its original axis, usually occurring on the outer wall of a curvature. Flexible NiTi files significantly reduce transportation compared to stainless steel.

The inadvertent pushing of dentin chips, pulp tissue, or irrigant beyond the apical foramen during instrumentation. Reciprocating motion and crown-down approaches may help minimize extrusion.

The geometric profile of a file when viewed in transverse section. Common designs include triangular, S-shaped, rectangular, and parallelogram; each affects cutting efficiency, flexibility, and debris removal.

A post-manufacturing thermal process applied to NiTi alloys to modify their phase-transformation behavior. Heat-treated files generally show improved flexibility and cyclic fatigue resistance.

A property of certain heat-treated NiTi alloys that lack the superelastic snap-back of conventional NiTi. Controlled-memory files can be pre-curved to match canal anatomy before insertion.

The ability of a NiTi alloy to return to its original shape after deformation when heated above its transformation temperature. Conventional NiTi files use this property to straighten after bending in the canal.

A manufacturer designation indicating a file is intended for one patient only. Single-use eliminates cross-contamination risk and avoids the cumulative fatigue of repeated sterilization cycles.

A file designed for multiple uses after proper cleaning, inspection, and sterilization. Manufacturers typically specify a maximum cycle count; files should be discarded if unwinding, corrosion, or deformation is detected.

A gentle, short in-and-out apical advancement (1-3 mm) used during instrumentation. Each peck cuts a small amount of dentin before the file is withdrawn for cleaning and irrigation.

A lateral sweeping movement used mainly in the coronal and middle thirds to selectively remove dentin from the outer canal wall, particularly useful for flared or oval-shaped canals.

A manual oscillating technique where a hand file is rotated 60-90 degrees clockwise then counterclockwise while advancing apically. It is commonly used during initial glide path negotiation.

Reinserting a small hand file (typically #10) to full working length between shaping instruments to confirm patency, break up debris packs, and maintain the glide path throughout the sequence.