Upper Jaw Impression Tray Retention Design
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Solution Overview
Problem
Existing plastic impression trays for upper jaws in dentistry face issues with set impression materials floating upward and being peeled off, leading to precision problems in dental prosthetic appliances due to insufficient retention mechanisms, particularly in plastic trays which struggle with forming effective undercut portions.
Innovation Solution
A plastic impression tray design featuring a U-like shaped bottom portion with a bulge, elongated through holes in the outer wall and circular holes in the bottom, optimized with specific dimensions such as hole width, length, and spacing to prevent floating and peeling, along with a rim to enhance retention and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If undercut portions (ribs) are formed along the peripheral portion of the tray to retain impression material, then mechanical retention is improved, but the plastic tray cannot be formed with effective undercut portions due to mold constraints, resulting in insufficient retention and peeling
Solution Approach 1:
The patent changes the geometric parameters of the tray edges by forming convex portions (ribs) with specific height ranges (0.5-2.0mm) and width ranges (1.0-3.0mm) along the peripheral portion. These parameter modifications create effective undercut portions that provide mechanical retention while being manufacturable in plastic materials through standard injection molding processes.
Solution Approach 2:
The patent segments the peripheral portion of the tray into multiple convex portions (ribs) distributed along the edges. This segmentation creates multiple discrete retention points that collectively provide sufficient mechanical retention while avoiding the need for large, complex undercut portions that would be difficult to manufacture in plastic.
2Ease of operation
If large force is applied to take out the set impression material from the oral cavity, then the impression material can be removed from the tray, but the set impression material floats upward and is peeled off from the tray, generating air gaps and deformation
Solution Approach 1:
The patent applies preliminary anti-action by forming convex portions (ribs) along the peripheral portion of the tray before the impression taking process. These ribs create mechanical interlocking features that prevent the set impression material from floating upward and peeling off during the removal process, thereby maintaining impression accuracy without requiring excessive removal force.
Solution Approach 2:
The patent implements preliminary action by pre-forming the convex portions (ribs) with specific dimensional characteristics (height: 0.5-2.0mm, width: 1.0-3.0mm) during tray manufacturing. These pre-formed features then serve as retention mechanisms during the clinical procedure, preventing peeling and maintaining precision without requiring additional corrective actions.
3Ease of operation
If the impression material is peeled off from the tray peripheral portion, then the impression material can be removed, but the impression material deforms from the initial set state and precision is significantly lowered
Solution Approach 1:
The patent applies preliminary anti-action by forming convex portions (ribs) with specific dimensional characteristics (height: 0.5-2.0mm, width: 1.0-3.0mm) along the peripheral portion of the tray. These ribs create mechanical interlocking features that prevent the set impression material from floating upward and peeling off during removal, thereby maintaining impression accuracy without requiring excessive removal force.
Data Source
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AI summary
The invention provides an impression tray for an upper jaw which is made of a plastic, can prevent a set impression material from floating upward from the tray and being peeled off from the tray, and can be used for taking an impression having a high precision. The impression tray has an outer wall (2), a bottom portion (1) forming a flat U-shaped surface with an approximately uniform width and a bulge portion (3) occluding the inner side space between the U-like shaped bottom portions (1). A rim (4) is provided along the upper end of the outer wall (2). Elongated through holes (5) extend vertically from just below the rim (4) to the bottom portion (1) in the outer wall (2). The distance between adjacent through holes is 2 to 5 times the width of said elongate through holes (5). Similar elongated through holes (6) are provided in the bulge portion (3). Circular through holes (7) and elongated through holes (8) are provided in the bottom portion (1).