Plunger Assembly with Segmented Screw Thread for Dental Dispensing

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Solution Overview

Problem

Existing dispensing devices for dental composite filling materials require high forces due to their high viscosity, are often expensive, and do not adequately address hygiene concerns, making them difficult to use and handle effectively.

Innovation Solution

A plunger assembly with a unique continuous screw thread and nut thread design that allows for precise, controlled dispensation of dental materials, minimizing afterflow and contamination, and featuring a retention structure for easy assembly and handling, including a seal and handle for reduced contamination and ergonomic handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional dispensing devices are used for high viscosity dental materials, then dispensing force is sufficient, but device complexity and cost increase

Engineering Contradiction:
Improvedispensing forceVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The continuous screw thread is segmented into distinct first and second thread portions with different shapes, allowing the plunger assembly to function as a self-contained unit that integrates both high-force generation and precise positioning capabilities without requiring complex external mechanisms

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The plunger assembly merges multiple functions into a single integrated component: the first thread portion engages with the container for material advancement, the second thread portion engages with the plunger body for force transmission, and the retention structure combines assembly retention with dispensation control, eliminating the need for separate instruments

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If conventional dispensing devices are used, then material can be dispensed, but hygiene and contamination control are insufficient

Engineering Contradiction:
Improvedispensing efficiencyVSAvoidcontamination
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The retention structure extracts the dispensation control function from external instruments and integrates it into the plunger assembly itself, allowing the second thread portion to engage with the plunger body in a controlled manner that minimizes contamination risk during both assembly and dispensation operations

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The integrated plunger assembly design allows for disposable or single-use configurations where the entire assembly can be discarded after use, eliminating cross-contamination risks between patients while maintaining cost-effectiveness through simplified manufacturing

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If conventional dispensing devices are used, then material dispensing is possible, but precise dosage control is difficult

Engineering Contradiction:
Improvehandling convenienceVSAvoiddosage precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The invention changes the geometric parameters of the screw thread by creating two distinct thread portions with different shapes, where the first thread portion provides coarse advancement and the second thread portion provides fine control, enabling precise dosage measurement through the differential thread geometry

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The retention structure replaces complex mechanical dosing mechanisms with a simplified thread engagement system where the interaction between the second thread portion and plunger body automatically provides precise dosage control through controlled displacement

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If separate instruments are used for material separation, then dispensing can be controlled, but device complexity and hygiene risks increase

Engineering Contradiction:
Improvedosage controlVSAvoidinstrument requirements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention merges the dosing control function into the plunger assembly by integrating the retention structure with the second thread portion, allowing dosage control to be achieved through the same component that advances the material, eliminating the need for separate dosing instruments

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The plunger assembly achieves multi-functionality where the first thread portion handles container engagement and material advancement, the second thread portion handles plunger body engagement and force transmission, and the retention structure handles both assembly retention and dispensation control, making the single component universally functional

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables efficient, precise, and hygienic dispensation of dental materials with reduced afterflow and contamination, facilitating convenient handling and storage, while minimizing the need for additional instruments, thus addressing the challenges of high viscosity and hygiene in existing devices.

Implementation Method 1

a screw (11) which comprises a first thread portion (111) and a second thread portion (112), the first and second thread portion (111, 112) differ in shape, the first and second thread portion (111, 112), in combination, form one continuous screw thread

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3325052B1A device comprising a plunger assembly, a method of assembling the device and a method of making the plunger assembly
Publication Date: 2020.02.19 3M INNOVATIVE PROPERTIES CO
  • EP3325052B1 patent drawingFigure 1~2
  • EP3325052B1 patent drawingFigure 3
  • EP3325052B1 patent drawingFigure 4

AI summary

A device for dispensing a material, being provided with a plunger assembly which has a screw with a first thread portion and a second thread portion. The first and second thread portion differ in shape and, in combination, form one continuous screw thread. The plunger assembly further has a nut which engages the screw thread by a nut thread. The nut thread corresponds in shape to a negative shape of the first thread portion. The invention help minimizing efforts in the assembly of a device using the plunger assembly.