Shell Tooth Repositioner Attachment Torque Control
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Solution Overview
Problem
Existing shell-shaped tooth repositioners face challenges in applying a repositioning force system with the appropriate magnitude and direction, often resulting in excessive tooth movement due to tipping torque, necessitating additional attachments and adhesions to achieve desired orthodontic outcomes.
Innovation Solution
The development of an attachment and shell-shaped tooth repositioner assembly, where the attachment's force-applying surface direction is determined based on the movement tendency of the repositioner relative to the tooth, and the geometry of the attachment-receiving cavity is designed to engage the attachment, converting relative movement into desired forces or torques to prevent tipping during translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a shell-shaped tooth repositioner is used to move a tooth in mesial or distal direction, then the desired translation movement is achieved, but a large tipping torque is generated causing excessive movement of the incisal edge and undesired tipping
Solution Approach 1:
An attachment is introduced as an intermediary element between the shell-shaped repositioner and the tooth. The attachment includes a force-applying surface that engages with the repositioner to convert the relative movement tendency into a desired force or torque, specifically generating a counter-torque to prevent tooth tipping during translation
Solution Approach 2:
The attachment is designed to generate a counter-torque that opposes the tipping torque produced by the repositioner. By positioning the force-applying surface at a specific angle (5°-45° relative to the occlusal plane) and location on the tooth, the system creates a balancing moment that prevents excessive incisal edge movement while maintaining translation
2Manufacturing precision
If an attachment is added to prevent tooth tipping, then the repositioning force system accuracy is improved, but the device complexity increases due to additional components and adhesion procedures
Solution Approach 1:
The attachment geometry is optimized by controlling specific parameters: the force-applying surface angle (5°-45° to occlusal plane), vertical distance from biting edge (0.5-3.0 mm), and horizontal distance from distal end (0.5-3.5 mm). These parameter optimizations enable effective torque generation with relatively simple attachment structures
Solution Approach 2:
The attachment-receiving cavity is integrated into the shell-shaped repositioner structure, and the attachment is combined with the tooth via adhesion. This merging of components creates a unified force transmission system that achieves precise force control without requiring separate, complex mechanisms
Data Source
AI summary
Disclosed is an attachment and a shell-shaped tooth repositioner assembly for repositioning a dentition from a first tooth arrangement to a second tooth arrangement, the assembly comprises a first attachment and a shell-shaped tooth repositioner, wherein the first attachment is a raised element fixed on a first tooth and forms a first force-applying surface to be applied a force thereon by the shell-shaped tooth repositioner and transferring the force to the first tooth, wherein the facing direction of the first force-applying surface is determined based on a movement tendency relative to the first tooth of a part of the shell-shaped tooth repositioner covering the first tooth, the shell-shaped tooth repositioner is an integral shell which forms a cavity receiving the dentition and a first attachment-receiving cavity receiving the first attachment, the first attachment-receiving cavity engages the first attachment when the shell-shaped tooth repositioner is worn on the dentition.