Digital Aligner Trimline Modeling for Complex Edge Machining

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Solution Overview

Problem

Current methods for manufacturing orthodontic aligners face challenges such as difficult trimming of complex shapes, high costs associated with CNC milling, and limitations in achieving optimal edge quality, which can prolong treatment and compromise patient comfort.

Innovation Solution

A method and system for defining a trimline for aligner manufacturing, involving the use of a point cloud representing a three-dimensional model of intraoral surfaces, to generate a digital trimline that can be edited and validated, allowing for precise machining and improved aligner performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If manual trimming with scissors is used, then flexibility in trimming complex shapes is improved, but time consumption and skill requirement increase significantly

Engineering Contradiction:

Improveflexibility in trimmingVSAvoidtime consumption

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical trimming with automated CNC milling machinery. The system uses computer-controlled milling tools to automatically trim aligners based on digitally defined trimlines, eliminating the need for manual scissors trimming while maintaining precision and reducing time consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transforms the trimming process from manual to automated by changing key parameters: the trimline definition moves from visual estimation to precise digital coordinates, and the trimming action changes from manual cutting to automated CNC milling with controlled feed rates and depths.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If CNC milling is used for trimming, then productivity and precision are improved, but setup complexity and cost increase

Engineering Contradiction:

Improvetrimming speedVSAvoidsetup procedure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions by digitally defining the trimline and creating the machining program before the actual trimming operation. The system calculates the optimal toolpath and prepares all necessary parameters in advance, which simplifies the actual CNC setup and reduces on-site complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses digital copying of the patient's dentition model to create a virtual representation. The trimline is defined on this digital copy, and the machining program is generated from the digital model, allowing the physical trimming to be precisely replicated without complex manual setup procedures.

Inventive Principle:

Principle #26Copying

3Productivity

If CNC milling is used, then most aligners can be trimmed automatically, but some aligners cannot be completely separated due to spatial limitations

Engineering Contradiction:

Improveautomated trimming capabilityVSAvoidcomplete separation achievement

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a dynamic trimming approach where the CNC milling process uses multiple passes with varying depths and toolpaths. The system adjusts machining parameters dynamically based on the specific geometry of each aligner, allowing complete separation even in difficult spatial configurations that static single-pass methods cannot achieve.

Inventive Principle:

Principle #15Dynamics

4Productivity

If CNC milling is used, then trimming efficiency is improved, but edge quality requires subsequent processing to remove burrs and sharp edges

Engineering Contradiction:

Improvetrimming efficiencyVSAvoidedge quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent merges multiple operations into a single integrated CNC machining process. The trimming, deburring, and edge rounding operations are combined into one continuous automated process, eliminating the need for separate subsequent processing steps while maintaining high edge quality.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250044768A1Systems and methods for designing and manufacturing an orthodontic appliance

Publication Date: 2025.02.06 ORMCO CORP

AI summary

Systems and methods of defining a trimline in relation to modeled teeth including a three-dimensional model of one or more intraoral surfaces of the patient. The trimline is for use to manufacture an aligner. For one or more pairs of adjacent teeth, a scallop plane is defined based on a scallop factor. The scallop plane is used to determine the position of scallop points on a line around each tooth adjacent to an interproximal region of the pair of teeth. Transition points are then defined on the line around each tooth apically of the scallop points, and the points connected to form an initial connector curve. The initial connector curve is projected on to a mesh of the three-dimensional model, and smoothing applied to the resulting segmented connector curve. The smoothed connector curves are then joined by teeth curves to form the trimline.