Endodontic Slot Geometry for Flexibility Without Strand Slippage

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Solution Overview

Problem

Existing endodontic instruments with longitudinal slits face issues of strand slippage and cohesion loss, leading to potential breakage and inefficient cutting, and lack of control over edge sharpness and flexibility.

Innovation Solution

Endodontic instruments with non-rectilinear longitudinal slots that form helical or concave/convex shapes, manufactured using wire electrical discharge machining with a cutting wire at an angle, allowing precise control over strand movement and edge sharpness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a longitudinal slot is introduced to increase flexibility and create sharp edges, then cutting efficiency and adaptability improve, but strand slippage and cohesion loss occur leading to potential breakage

Engineering Contradiction:
ImproveflexibilityVSAvoidcohesion
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies curvature by forming the longitudinal slot with a non-rectilinear shape, specifically using a curved or helical path rather than a straight line. This curved configuration allows the slot to follow the natural curvature of the root canal while maintaining strand cohesion through controlled geometry, preventing slippage while preserving flexibility and cutting efficiency

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If strands are allowed to move relative to each other for flexibility, then adaptability to curved canals improves, but control over edge sharpness and cohesion is lost

Engineering Contradiction:
Improveadaptability to curved canalsVSAvoidedge sharpness control
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The curved or helical configuration of the longitudinal slot provides geometric control over strand movement. The curvature radius and path are designed to allow controlled relative movement that maintains edge sharpness while adapting to canal curvature, preventing uncontrolled slippage that would compromise manufacturing precision

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If a longitudinal slot divides the instrument into separate strands, then flexibility and irrigation fluid guidance improve, but strand slippage creates excessive peripheral edges deviating from the rotation axis

Engineering Contradiction:
Improveirrigation fluid guidanceVSAvoidperipheral edge position
Core Design Contradiction:
Ease of operationVSShape

Solution Approach 1:

The non-rectilinear, curved configuration of the longitudinal slot constrains strand movement to follow a controlled path, preventing excessive peripheral deviation from the rotation axis. The curvature geometry ensures that even when strands move relative to each other for irrigation fluid guidance, the peripheral edges remain within acceptable positional tolerances

Inventive Principle:
Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances instrument flexibility, cohesion, and cutting efficiency while maintaining control over edge sharpness, facilitating easier manufacturing and diverse instrument configurations.

Implementation Method 1

Another method, described in document FR2867995A1, involves machining metal rods using wire electrical discharge machining (EDM).

Methodology Applied
Scientific EffectElectrical discharge machining: Electrical Discharge Machining

Data Source

PatentEP4460262B1Endodontic instrument having a non-rectilinear longitudinal slot, and method for manufacturing such an instrument
Publication Date: 2025.12.03 NEOLIX
  • EP4460262B1 patent drawingFigure 1~2
  • EP4460262B1 patent drawingFigure 3~4
  • EP4460262B1 patent drawingFigure 5~6

AI summary

The invention relates to an endodontic instrument extending along a longitudinal axis (50), the instrument having at least one longitudinal slot (2), over at least part of its length, separating the instrument into a plurality of separate blades (51, 52). According to the invention, the slot (2) has a linear non-rectilinear shape in a cross-section perpendicular to the longitudinal axis (50).