Virtual Aligner Model Approval Using Cosine-Based Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining aligner retention are inadequate, leading to potential excessive resistance during removal, which can hinder the effectiveness and efficiency of dental aligner treatments.
Innovation Solution
A method that calculates the cosine of the angle between the surface normal and the spatial direction for triangles with angles greater than 90°, and uses the product of area and cosine for triangles with smaller angles to determine retention, ensuring the aligner's suitability for production by setting minimum and limit retention criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If retention is determined as the number or sum of angles greater than 90°, then the calculation is simple, but the determination of retention is inaccurate leading to potential excessive resistance during removal
Solution Approach 1:
The patent changes the parameter for retention calculation from a simple angle count to a cosine-based projection calculation. By using the cosine of angles between surface normals and removal direction, the method achieves more accurate retention determination while maintaining computational feasibility through automated processing.
Solution Approach 2:
The patent replaces the simple angular counting method with a physics-based cosine projection model. This substitution uses mathematical modeling to simulate the actual mechanical resistance forces, providing more accurate retention prediction without requiring complex physical testing.
2Ease of operation
If the aligner is designed with adequate retention, then the aligner may become too difficult to remove, but if retention is reduced for easy removal, then the aligner may not stay in place properly
Solution Approach 1:
The patent implements a feedback mechanism by calculating retention values and comparing them against predefined acceptable ranges. This allows iterative adjustment of the aligner design to achieve optimal retention - not too high to cause removal difficulty, not too low to compromise fit stability.
Solution Approach 2:
The patent enables dynamic optimization of retention characteristics by allowing adjustment of spatial removal directions and evaluating retention for multiple configurations. This dynamic approach finds the optimal balance between retention reliability and removal ease for each specific aligner design.
3Productivity
If manual assessment of retention is performed, then flexibility in evaluation is maintained, but the process is time-consuming and prone to human error
Solution Approach 1:
The patent implements an automated self-assessment system that calculates retention values without human intervention. The computational method automatically processes the 3D model, calculates cosine projections, and determines retention metrics, eliminating human error and significantly increasing assessment speed.
Solution Approach 2:
The patent replaces manual visual assessment with an automated computational model. This substitution uses algorithmic processing to objectively calculate retention based on geometric parameters, providing both higher speed and greater precision compared to subjective manual evaluation.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method for testing and releasing a virtual model (1) consisting of a number of triangles for the production of an aligner that covers teeth of a jaw and opposes retraction from the jaw in a spatial direction (d) is disclosed, wherein each of the triangles is assigned a unique index and an area, a surface normal pointing out of the jaw, an angle between the surface normal and the spatial direction (d), and a cosine of the respective angle (αi) are calculated, and the aligner is only released for production based on the model (1) if the retention is greater than a specified minimum retention and less than a specified limit retention, and otherwise the model (1) is rejected.To assess the retention of the aligner using model (1), it is proposed that for each of the triangles a projection to 0 is set if the respective angle is less than 90°, and otherwise the projection is determined as the product of the respective area with the cosine magnitude, and the retention is determined as the sum of the projections.