Asymmetric Root Canal Reamer Against Wall Screwing
Solution Overview
Problem
Existing root canal instruments with helical flutes tend to screw and engage with the canal walls, causing damage and injury due to their natural design, especially when dealing with non-circular sections.
Innovation Solution
A root canal instrument with a cylindrical or conical working zone featuring X helical flutes forming X cutting lips, where all cutting angles between successive lips are different, positioned on concentric circles of varying diameters, and without symmetry, designed to increase asymmetry and reduce the likelihood of screwing by varying the angles and helix positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If helical flutes are used to form cutting edges, then the instrument can effectively cut and prepare the canal, but the instrument tends to screw and engage with the canal walls, causing damage and injury
Solution Approach 1:
The patent applies asymmetry by making all cutting angles between successive cutting lips different, eliminating symmetry in the cross-section. This asymmetric configuration prevents the instrument from screwing into the canal walls while maintaining effective cutting capability, directly resolving the technical contradiction between productivity and harmful engagement.
2Ease of manufacture
If the instrument has a symmetrical cross-section, then manufacturing is simpler, but the instrument cannot effectively handle non-circular canal sections and still tends to twist and dig into walls
Solution Approach 1:
The patent deliberately introduces asymmetry by positioning cutting edges on concentric circles of different diameters with different cutting angles, creating a non-symmetrical cross-section. This design enables the instrument to adapt to non-circular canal sections and prevents twisting, resolving the contradiction between manufacturing simplicity and adaptability.
Solution Approach 2:
The patent applies local quality by varying the cutting angles and positions of individual cutting lips around the circumference. Each cutting lip has specific local characteristics (different angles and radial positions) that collectively provide adaptability to non-circular sections while maintaining manufacturability through systematic variation.
3Ease of manufacture
If all cutting edges are positioned at the same diameter, then the cross-section remains circular and manufacturing is easier, but the instrument cannot effectively prepare non-circular canal sections
Solution Approach 1:
The patent positions cutting edges on concentric circles with different diameters, creating an asymmetric cross-sectional profile. This design enables effective preparation of non-circular canal sections while maintaining reasonable manufacturing complexity through the systematic arrangement of cutting edges at varying radial distances.
Data Source
Figure 1~2b
Figure 3a~4c
AI summary
The invention relates to a dental reamer root canal instrument comprising a working area that is substantially cylindrical or conical along a longitudinal axis, the instrument including X helical flutes forming X lips of helical cuts, a cut lip being formed by the intersection of two consecutive flutes, wherein X is equal to or greater than three, the instrument being characterized in that, over a cross-section of the instrument, the angles (aI,ßI, ?I) between two consecutive cut lips, measured relative to the longitudinal axis of the instrument, are all different. The invention likewise relates to a method for producing a root canal instrument according to the invention in a cylindrical or conical rod. The rod is made of e.g. a metal or metal alloy, e.g. a nickel-titanium alloy, which is selected for the mechanical bending strength and shape memory properties thereof. The method includes a series of steps for using a grinding wheel to machine a flute to a predefined depth and steps for rotating the rod in front of the machining wheel.