Root Canal Cutting Tool Reverse Rotation Control

Solution Overview

Problem

In root canal treatment, shavings generated during cutting are often pushed back towards the root apex when the file is rotated in reverse, leading to contamination and reduced treatment success, and excessive load can cause file breakage with fragments left in the canal, complicating removal.

Innovation Solution

A root canal treatment apparatus with a handpiece, drive portion, and control system that reversely rotates the cutting tool by a predetermined angle when it reaches a set position, then stops rotation, preventing shavings from being pushed back towards the apex and reducing the risk of file breakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the file is rotated in reverse rotation direction to avoid breakage and release biting into root canal wall, then file safety is improved, but shavings are pushed back towards root apex causing contamination

Engineering Contradiction:

Improvefile safetyVSAvoidshavings contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic action by alternating between forward rotation (cutting direction) and reverse rotation (safety direction) at specific intervals. The control unit switches rotation direction based on detected load conditions, performing forward rotation during normal operation and reverse rotation when excessive load is detected or at predetermined positions, thereby periodically alternating between cutting efficiency and file safety modes.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent changes operational parameters by adjusting rotation direction based on detected conditions. The control unit monitors load on the file and changes the rotation parameter from forward to reverse direction when excessive load is detected or when reaching predetermined positions near the root apex, optimizing both file safety and contamination prevention.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the file is constantly rotated in forward direction to maintain cutting efficiency, then productivity is improved, but file breakage risk increases due to excessive load

Engineering Contradiction:

Improvecutting efficiencyVSAvoidfile breakage risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies periodic action by alternating between forward rotation (cutting direction) and reverse rotation (safety direction) at specific intervals. The control unit switches rotation direction based on detected load conditions, performing forward rotation during normal operation and reverse rotation when excessive load is detected or at predetermined positions, thereby periodically alternating between cutting efficiency and file safety modes.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements feedback by using a load detection unit to continuously monitor the load on the file during rotation. The control unit receives this feedback information and adjusts the rotation direction accordingly - maintaining forward rotation when load is within safe limits and switching to reverse rotation when excessive load is detected, thereby dynamically optimizing cutting efficiency while preventing file breakage.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If the file is stopped at root apex position and pulled out, then treatment precision is improved, but reverse rotation pushes shavings back causing contamination

Engineering Contradiction:

Improvetreatment precisionVSAvoidshavings contamination

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by performing forward rotation after the file reaches the predetermined position near the root apex before pulling it out. This forward rotation counteracts the natural tendency of reverse rotation to push shavings back towards the root apex, thereby preventing contamination while maintaining treatment precision. The control unit detects when the file reaches the predetermined position and switches to forward rotation to prevent shavings from being pushed back.

Inventive Principle:

Principle #9Preliminary anti-action

4Adaptability or versatility

If a superelastic material is used for the file to enable cutting along curved root canals, then adaptability is improved, but file breakage risk increases when excessive load is applied

Engineering Contradiction:

Improvecurved canal cutting abilityVSAvoidfile breakage risk

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements feedback by using a load detection unit to continuously monitor the load on the file during rotation. The control unit receives this feedback information and adjusts the rotation direction accordingly - maintaining forward rotation when load is within safe limits and switching to reverse rotation when excessive load is detected, thereby dynamically optimizing cutting efficiency while preventing file breakage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies periodic action by alternating between forward rotation (cutting direction) and reverse rotation (safety direction) at specific intervals. The control unit switches rotation direction based on detected load conditions, performing forward rotation during normal operation and reverse rotation when excessive load is detected or at predetermined positions, thereby periodically alternating between cutting efficiency and file safety modes.

Inventive Principle:

Principle #19Periodic action

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

This approach effectively prevents shavings from being left near the root apex, enhances the success rate of root canal treatment, and simplifies the removal of files by releasing the cutting tool from the canal wall, reducing the risk of file breakage and fragment retention.

Implementation Method 1

a root canal length measurement portion configured to electrically detect a position of a tip end of the cutting tool in a root canal, using the cutting tool as a measuring electrode

Methodology Applied

Scientific EffectElectrical detection: Conduction (electrical)

Data Source

PatentEP3597139B1Root canal treatment device

Publication Date: 2023.10.04 J MORITA MANUFACTURING CORP

Figure 1(a)~1(b)
Figure 2
Figure 3

AI summary

The present invention provides a root canal treatment apparatus in which biting of a blade of a cutting tool into a root canal wall can be released and push-back of shavings into a root canal can be suppressed, when a position of a tip end of the cutting tool reaches a predetermined set position and rotation of the cutting tool is stopped. The root canal treatment apparatus according to the present invention includes: a handpiece configured to hold a cutting tool in a head in a drivable manner; a motor driver and a micromotor configured to drive the cutting tool; a root canal length measurement circuit; and a control portion. The root canal length measurement circuit is configured to electrically detect a position of a tip end of the cutting tool in a root canal, using the cutting tool as a measuring electrode. The control portion is configured to perform drive for reversely rotating the cutting tool by a predetermined set angle (180 degrees) when the position of the tip end of the cutting tool detected by the root canal length measurement circuit reaches a predetermined set position, and then, stopping rotation.