Orthodontic Aligner Cavity Geometry for Attachment-Free Retention
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Solution Overview
Problem
Current methods for dental appliance retention, such as orthodontic aligners, suffer from low retention due to smooth surfaces, leading to reduced effectiveness in applying movement forces and increased costs and visibility of attachments.
Innovation Solution
The method involves generating 3D models of the patient's oral cavity, simulating retention forces on retentive and actual arches, and modifying aligner geometry by adjusting cut line offsets and radii to enhance frictional forces, thereby increasing retention without additional attachments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If smooth and uniform tooth surfaces are used, then the natural appearance and simplicity of the dental appliance is maintained, but the retention between teeth and the dental appliance is reduced
Solution Approach 1:
The patent applies local quality by creating non-uniform cavity surfaces only in specific regions where retention is needed, while maintaining smooth surfaces in other areas. The cavity surface is modified with varying roughness, peaks, and valleys localized to the tooth-appliance interface, rather than making the entire appliance surface complex.
Solution Approach 2:
The patent utilizes curvature principles by creating peaks and valleys with specific radii of curvature on the cavity surface. These curved features enhance mechanical interlocking between the appliance and tooth, improving retention through geometric interlocking rather than flat or uniformly smooth surfaces.
2Reliability
If attachments are added to increase retention, then the grip strength of the dental appliance is improved, but the cost and time for application increase
Solution Approach 1:
The patent extracts the retention function from separate attachments and integrates it directly into the appliance cavity structure. By incorporating retention features (peaks, valleys, and non-uniform surfaces) into the cavity itself, the need for additional attachment components is eliminated, reducing both material costs and application time.
Solution Approach 2:
The patent merges the retention function with the cavity structure by combining what were previously separate elements (cavity and retention features) into a single integrated component. The cavity surface itself provides both the fitting function and the retention function through its non-uniform geometry.
3Reliability
If attachments are added to improve retention, then the grip strength is increased, but the attachments may fall off during treatment and become visible creating aesthetic issues
Solution Approach 1:
The patent removes the separate attachment component that causes aesthetic problems and transfers its retention function to the cavity structure. By eliminating standalone attachments and embedding retention features within the cavity, the harmful aesthetic effect is removed while retaining the functional benefit.
Solution Approach 2:
The patent transitions from adding retention features in the horizontal plane (attachments on tooth surfaces) to creating retention through vertical dimension variations (peaks and valleys in the cavity depth). This dimensional approach to retention eliminates the need for visible lateral attachments.
4Reliability
If the aligner geometry is modified to increase frictional forces, then the retention is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying cavity surface parameters (roughness, peak height, valley depth, curvature radii) to optimize retention. These controlled parameter variations allow for improved retention while maintaining manufacturability through defined geometric parameters that can be precisely controlled during fabrication.
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 improves the retention of dental appliances, allowing for more predictable and effective tooth movement forces, reduces computing resource use, and enhances processing efficiency in dental treatment planning.
Implementation Method 1
tooth cavity deviations may increase the frictional forces between the aligner and the tooth allowing an aligner to more strongly grip the surface of a tooth
Data Source
AI summary
A method for designing dental appliances may include receiving a 3D model of the patient's oral cavity and determining a target arrangement of the patient's teeth from the 3D model. The method may also include generating a treatment plan for moving teeth of a patient from an initial position towards and final position over a plurality of stages. For a stage of the plurality of stages the method may include identifying which of the patient's teeth are for the stage of the treatment plan, modifying movement of the stationary teeth for the stage of the treatment plan, and revising the treatment plan using a modified movement of the stationary tooth for the stage of the plurality of stages to generate a revised treatment plan.