Flexible Endodontic Instrument Yield Strength
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Solution Overview
Problem
Conventional endodontic instruments made of high yield strength materials like stainless steel and nickel-titanium alloys cause unnecessary dentine loss and alter the natural anatomy of root canals during shaping, leading to potential ledging, stripping, and excessive removal of healthy dentine.
Innovation Solution
An endodontic instrument with a working part made of flexible material having an upper yield strength of less than 200 MPa, featuring an angular or offset axis, and a smaller diameter, allowing for precise shaping and preservation of the root canal's original anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional endodontic instruments made of high yield strength materials (stainless steel, nickel-titanium alloys) are used for root canal shaping, then the instrument has sufficient structural strength and cutting ability, but excessive dentine material is removed and the natural root canal anatomy is altered
Solution Approach 1:
The patent changes the material parameter (yield strength) from conventional high strength materials (>200 MPa) to a flexible material with upper yield strength of less than 200 MPa. This parameter change allows the instrument to deform elastically during engagement with dentine and return to its original shape, removing only the minimal amount of dentine necessary for shaping while preserving the natural root canal anatomy.
2Reliability
If high yield strength materials are used for root canal shaping, then complete removal of infected material is achieved, but ledging and stripping perforations occur due to excessive shaping
Solution Approach 1:
By changing the material parameter to low yield strength (<200 MPa), the instrument becomes flexible enough to conform to the natural root canal path without creating ledges or stripping the walls. The elastic deformation and recovery mechanism ensures that the instrument follows the natural anatomy rather than forcing a predetermined shape, thereby eliminating harmful effects while maintaining effective cleaning.
3Force
If conventional stainless steel or nickel titanium alloys with substantial austenite share are used, then the instrument has high restoring force for cutting, but unnecessary weakening of dentinal walls occurs
Solution Approach 1:
The patent inverts the force mechanism by using a material with low yield strength that deforms elastically under cutting loads rather than maintaining high restoring force. The instrument material yields and deforms during engagement with dentine, then returns to its original shape, transferring minimal force to the dentinal walls and avoiding unnecessary weakening while still achieving effective cutting through repeated elastic deformation.
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
The instrument effectively removes pulp tissue and debris while minimizing dentine loss, maintaining the root canal's original shape and position, with reduced risk of ledging and stripping, and economic advantages in material usage.
Implementation Method 1
the working part is made of a flexible material having an upper yield strength of less than 200 MPa
Implementation Method 2
a working part with an abrasive surface, which extends from the base portion
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to an endodontic instrument for anatomically shaping a root canal of a human tooth, having a base portion, which can be mounted on a holding device and can be rotated around a reference axis A, and having a working part with an abrasive surface, at least a part of which extends from the base member and has an axis which is arranged angular with respect to a reference axis, wherein the central axis of the base portion and the central axis of working portion enclose an angle α greater than zero, and/or wherein the central axis of the working portion is offset in parallel to the reference axis of the base member by a distance r , characterised in that the working part is made of a flexible material having a yield strength of less than 200 MPa.