The Effects of Different Attachment Types and Positions on Rotation Movement in Clear Aligner Treatments: A Finite...

Area of Science:

• Orthodontics
• Biomaterials Engineering
• Dental Mechanics

Background:

• Achieving accurate rotation of mandibular premolars with clear aligners presents a clinical challenge.
• Attachment design and placement are crucial for effective clear aligner therapy outcomes.
• Understanding stress distribution in the periodontal ligament (PDL) is vital for predicting treatment success and patient comfort.

Purpose of the Study:

• To compare the efficacy of various clear aligner attachment types and positions for rotating mandibular first premolars.
• To evaluate the impact of different attachments on clear aligner retention during rotation.
• To analyze stress values within the periodontal ligament (PDL) using finite element analysis (FEA) for different attachment configurations.

Main Methods:

• A mandibular tooth model with a 30° rotated first premolar was developed.
• Twelve groups were created with horizontal rectangular, vertical rectangular, ellipsoid, and semi-ellipsoid attachments in buccal, lingual, and combined placements, plus a control group.
• Finite element analysis (FEA) was employed to assess clear aligner displacement, PDL stress (von Mises), and tooth displacement following a 0.25 mm activation.

Main Results:

• The horizontal rectangular attachment group (buccal and lingual) exhibited the highest PDL stress (0.1971 MPa) and tooth displacement (0.1267 mm).
• Semi-ellipsoid attachments placed buccally and lingually resulted in the least clear aligner displacement (0.1441 mm).
• All tested attachment groups demonstrated superior retention compared to the no-attachment control group.

Conclusions:

• Attachments enhance clear aligner retention for rotating mandibular premolars.
• Horizontal rectangular attachments, while effective for movement, induce higher stress and displacement.
• Combined buccal and lingual horizontal rectangular attachments are recommended for clinical application in rotating mandibular first premolars due to their efficacy in tooth movement.