Mouth Opening Instrument Reference Tooth Engagement

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Solution Overview

Problem

Conventional mouth-opening measuring instruments lack clear directions for use, leading to unstable and inaccurate measurements due to undefined criteria for which parts to touch and distances to measure, resulting in reduced measurement accuracy and reproducibility.

Innovation Solution

A mouth-opening measuring instrument with a defined engagement part for a reference tooth, a measuring surface with scale marks indicating distance and lateral displacement, and gripping surfaces for stability, using specific reference teeth as fulcrum points for accurate measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional mouth-opening measuring instruments without defined reference points are used, then the device structure is simple, but measurement accuracy and reproducibility deteriorate

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidinstrument structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measuring instrument is segmented into distinct functional parts: an engagement part for the first reference tooth and a measuring surface for the second reference tooth. This segmentation allows each part to have a specific function, improving measurement accuracy without significantly increasing overall complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The instrument incorporates specific local features such as scale marks positioned at defined locations relative to the engagement part, and a measuring surface with specific geometric properties. These local quality enhancements enable accurate measurement while maintaining a relatively simple overall structure

Inventive Principle:
Principle #3Local quality

2Reliability

If conventional mouth-opening measuring instruments without clear usage criteria are used, then the device is easy to operate, but measurement reproducibility deteriorates

Engineering Contradiction:
Improvemeasurement reproducibilityVSAvoidusage complexity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The instrument is designed with pre-defined reference teeth and predetermined engagement positions established before measurement begins. The first and second reference teeth are identified in advance, and the engagement part and measuring surface are positioned according to predetermined criteria, ensuring reproducible measurements without requiring complex operational procedures

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The instrument utilizes the patient's own anatomy (specific reference teeth) as built-in reference points. The first reference tooth in one jaw and the second reference tooth in the other jaw serve as self-contained reference elements, eliminating the need for external reference standards or complex alignment procedures

Inventive Principle:
Principle #25Self-service

3Measurement precision

If scale marks are added to indicate distance and lateral displacement, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoidscale mark system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The scale marks on the measuring surface serve multiple functions: they indicate both the distance from the engagement part and the lateral displacement of the second reference tooth. This multi-functionality improves measurement precision without requiring separate measurement systems, thereby limiting the increase in device complexity

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

Data Source

PatentEP3040049B1Opening measurement instrument
Publication Date: 2020.08.26 NAT UNIV CORP TOKYO MEDICAL & DENTAL UNIV
  • EP3040049B1 patent drawingFigure 1
  • EP3040049B1 patent drawingFigure 2
  • EP3040049B1 patent drawingFigure 3

AI summary

Provided is an opening measurement instrument which exhibits excellent instrument stability during measurement, and excellent measurement accuracy and reproducibility thereof. This opening measurement instrument is provided with: an engagement part which measures an opening amount between an upper jaw and a lower jaw, and which engages with first reference teeth in one of the jaws; a measurement surface which, while the engagement part is in a state of being engaged with the first reference teeth, is brought into contact with second reference teeth in the other jaw; and a first scale which is provided to the measurement surface, and which indicates the distance from the engagement part. The opening measurement instrument is preferably further provided with a second scale which is provided to the measurement surface, and which indicates the position of a direction orthogonal to the direction in which the first scale is provided. The measurement surface is preferably configured from a curved surface in which the measurement surface between the engagement part and a prescribed point of the measurement surface bulges with respect to a flat surface connecting the engagement part and the prescribed point of the measurement surface. Furthermore, the curved surface is preferably provided with a section having a curvature which increases as the distance from the engagement part increases.