Dental File Guide Tip with Reduced Contact Area

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Solution Overview

Problem

Existing endodontic files face breakage due to a large contact area at the tip, which causes resistance and impedes progression in root canal procedures, as they encounter surface irregularities and projections during rotation.

Innovation Solution

A dental instrument with a guide tip having a reduced cross-sectional contact area, defined by a conical-shaped envelope with specific face surfaces and a portion removed to create an arcuate or angled profile, allowing for a central guide point and minimizing contact with the canal walls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the file tip has a large contact area face surface, then the file provides stable engagement and control, but the file encounters increased resistance and risk of breakage when progressing through the root canal

Engineering Contradiction:
Improvefile stability and controlVSAvoidfile resistance to breakage
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The file tip is designed with non-uniform face surfaces where different portions have different contact characteristics. Specifically, the first face surface has a larger contact area for stable engagement, while the second face surface has a reduced contact area to minimize resistance. This local differentiation allows the file to simultaneously achieve stability where needed and reduced resistance where needed, resolving the contradiction between reliable engagement and breakage resistance.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the file tip has a large contact area face surface, then the file maintains good control during manipulation, but the file progression is impeded by surface irregularities and projections in the root canal

Engineering Contradiction:
Improvefile manipulation controlVSAvoidfile progression speed
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The file tip incorporates face surfaces with locally differentiated contact areas. The first face surface maintains a larger contact area to preserve manipulation control, while the second face surface reduces contact area to enable smoother progression through irregularities. This localized variation in contact area allows the file to maintain ease of operation while improving progression speed through the root canal.

Inventive Principle:
Principle #3Local quality

3Strength

If the file tip has reduced cross-sectional contact area, then the file experiences reduced resistance and breakage risk, but the file may lose precision in controlling the preparation shape

Engineering Contradiction:
Improvefile resistance to breakageVSAvoidcanal preparation shape control
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The file tip design applies local quality by differentiating the contact area of different face surfaces. The first face surface maintains a larger contact area to preserve precision in controlling the preparation shape, while the second face surface has a reduced contact area to minimize resistance and breakage risk. This selective differentiation resolves the contradiction between strength and manufacturing precision by applying different contact area characteristics to different functional regions of the file tip.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2140828B1Dental file with improved tip configuration
Publication Date: 2016.08.31 JOHNSON WILLIAM B
  • EP2140828B1 patent drawingFigure 1~2A
  • EP2140828B1 patent drawingFigure 3~4A
  • EP2140828B1 patent drawingFigure 5~5A

AI summary

A dental instrument for cleaning and shaping a root canal of a tooth includes a working portion having three helical flutes and a guide tip with a first, second, and third face surface. A portion of the guide tip is removed so that each of the first and second surfaces are contiguous to a lateral surface of a conical-shaped envelope defining the original tip but a portion of the third surface is not contiguous to a lateral surface of the conical-shaped envelope. The intersection of the first and second surfaces, however, remains at the center point of the guide tip. The removed portion of the guide tip may result in an arcuate-shaped face surface, an angular-shaped face surface, or some combination of the two.