Lip Cheek Holder With Low Friction Sliding Element
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Solution Overview
Problem
The existing lip/cheek holders used in dental procedures suffer from a 'stick-slip effect' when intraoral scanners with metallic shafts come into contact with the elastomer film, disrupting the scanning process due to increased contact pressure, especially when patients close their mouths, leading to jerky movements and potential infection risks.
Innovation Solution
The film of the lip/cheek holder is treated with a sliding element, such as an atomic deposition coating or surface modification, to reduce the coefficient of sliding friction, ensuring a uniform sliding movement and preventing the stick-slip effect without increasing film thickness or using loose lubricants, thus maintaining sterility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a highly lubricated film is used to reduce friction between the shaft and the film, then the stick-slip effect is reduced, but the film thickness must be increased which compromises its flexibility and conformability to the patient's mouth
Solution Approach 1:
The patent applies a sliding element (coating or surface modification) only on the inner surface of the film where contact with the shaft occurs, rather than throughout the entire film structure. This localized treatment reduces friction at the contact interface while preserving the bulk elastomer's flexibility and thin profile, resolving the contradiction between sliding smoothness and film flexibility.
Solution Approach 2:
The patent replaces the mechanical approach of increasing bulk film thickness for lubrication with a surface-level solution (coating or surface modification). This substitution allows friction reduction without compromising the film's structural properties, maintaining both sliding smoothness and flexibility simultaneously.
2Shape
If the film is made thinner to conform smoothly to the patient's mouth, then its flexibility and conformability improve, but its tear resistance decreases
Solution Approach 1:
The patent creates a composite structure by combining the elastomer film with a sliding element (coating or surface modification layer). This composite approach allows the thin film to maintain flexibility and conformability while the surface treatment provides enhanced durability and friction reduction, resolving the contradiction between conformability and tear resistance.
3Measurement precision
If the scanner moves at constant speed for accurate 3D scanning, then measurement precision improves, but the stick-slip effect causes jerky movements that disrupt scanning continuity
Solution Approach 1:
The patent changes the surface parameters of the film by applying a coating or surface modification that alters the coefficient of friction. This parameter change eliminates the stick-slip effect, allowing the scanner to move at constant speed without jerky interruptions, thereby maintaining both scan accuracy and scanning continuity.
4Stability of the object's composition
If the film is highly elastic to maintain flexibility, then its ability to conform to the mouth improves, but the rubber-like properties increase friction causing the stick-slip effect
Solution Approach 1:
The patent applies surface treatment only to the inner surface of the film where shaft contact occurs, preserving the bulk elastomer's high elasticity and flexibility while locally modifying the surface to reduce friction and eliminate the stick-slip effect, thus resolving the contradiction between elasticity and sliding smoothness.
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 ensures a trouble-free workflow by minimizing contact pressure forces, preventing the stick-slip effect, and maintaining the film's tear resistance, allowing for smooth and continuous scanning even under increased contact pressures, while ensuring a sterile environment.
Implementation Method 1
The sliding element has a significantly lower coefficient of sliding friction than a typical rubber-like elastomer. This coefficient can be, for example, 1.5 or 1.0.
Implementation Method 2
The sliding element can be either a coating produced by atomic deposition or a surface modification.
Data Source
Figure 1~2
Figure 3~5
AI summary
A lip/cheek retractor, particularly suitable for use with an intraoral scanner, is provided, comprising a film made of an elastomer, a lip ring, and a vestibular ring. This film extends between the lip ring and the vestibular ring, is held taut by them, and forms a tubular section between them. The film (20) is pre-equipped on its inner surface (32) of its tubular section with a sliding element (36), produced by a surface treatment and firmly bonded to the film (20), which modifies the surface of the film (20) in that area. This sliding element has a coefficient of sliding friction µG of less than 1.5, preferably less than 1.