Segmented Endodontic Instrument with Offset Mass Zones
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Solution Overview
Problem
Existing dental root canal drilling instruments face challenges in achieving the right balance of flexibility and strength, often leading to screwing into the canal, bending, or breaking, while also struggling to maintain optimal dimensioning and debris evacuation, especially in the apical portion.
Innovation Solution
The design features a rod with a tapered active part having a first portion with its center of mass on the axis of rotation and a second portion with an offset center of mass, providing a centered point for precise shaping and flexible, adjustable flexibility through progressive offset and alternating centred and off-centre zones, reducing the risk of screwing and debris retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the instrument is made more flexible to follow the curvature of the dental root canal, then it can navigate complex canal paths, but it may bend or break before completing the operation
Solution Approach 1:
The instrument is divided into multiple sections along its length, with each section having different flexibility characteristics. The proximal sections are more flexible to navigate curvatures, while the distal cutting section maintains sufficient rigidity for effective cutting and dimensional control.
Solution Approach 2:
Different portions of the instrument have different mechanical properties tailored to their specific functions. The proximal end is designed with higher flexibility for navigation, while the distal cutting end maintains optimal rigidity for precision work, creating localized quality variations along the instrument length.
2Adaptability or versatility
If the instrument axis is offset to improve flexibility and follow complex curves, then it can navigate better, but it generates a beating motion of the point within the canal making dimensioning difficult
Solution Approach 1:
The instrument shaft is segmented into multiple sections with varying degrees of offset. Only certain proximal sections have offset axes to provide flexibility, while the distal cutting section and its point maintain a centered axis to eliminate beating motion and ensure precise dimensioning.
Solution Approach 2:
The offset characteristic is applied locally only to specific sections of the instrument where flexibility is needed, while the critical cutting point and its immediate vicinity maintain a centered axis for precision, creating localized quality differences in the axis alignment.
3Adaptability or versatility
If the instrument axis is offset to increase flexibility, then it can follow canal curves better, but it pushes debris back towards the apical portion rather than evacuating it
Solution Approach 1:
The instrument design segments the flexibility function from the debris evacuation function. Flexibility is provided by offset sections in the proximal shaft, while the distal cutting section maintains proper flute geometry and axis alignment to ensure debris is ejected apically rather than pushed back.
Solution Approach 2:
The offset axis characteristic is applied locally only where needed for flexibility, while the critical cutting and debris ejection zone maintains proper alignment and flute configuration to ensure effective debris evacuation, preventing harmful debris retraction.
4Productivity
If continuous rotation is used for drilling, then the cutting action is effective, but the instrument has a tendency to screw itself into the canal
Solution Approach 1:
The instrument design segments the cutting function from the screwing tendency. The flutes are configured with specific pitch and orientation characteristics that provide effective cutting through continuous rotation while minimizing the screwing effect that would drive the instrument into the canal wall.
Solution Approach 2:
The flute geometry and pitch are optimized locally at the cutting point to provide efficient material removal through rotation, while the overall instrument design and flute configuration minimize the harmful screwing action, creating localized quality in the cutting mechanism.
Data Source
AI summary
An endodontic instrument that includes a tapered rod, the rod including an active portion and a distal end, the active portion defining an envelope having a longitudinal axis that coincides with an axis of rotation of the instrument.