[Finite element analysis of clear aligners in extractive cases].

Area of Science:

• Orthodontics
• Biomaterials Engineering
• Dental Mechanics

Background:

• Clear aligners are increasingly used for orthodontic treatment.
• Understanding the biomechanical principles of space closure with clear aligners is crucial for predictable outcomes.

Purpose of the Study:

• To analyze the mechanical characteristics of extraction space closure using clear aligners.
• To compare the stress distribution and anchorage requirements of different clear aligner retraction strategies.

Main Methods:

• A finite element analysis (FEA) model was developed based on a patient with four first premolar extractions.
• Four clear aligner space closure scenarios were simulated: anterior retraction (entire/dispersed) and posterior movement (mesial/dispersed).

Main Results:

• Anterior retraction: force distribution varied with existing anterior space, influencing anchorage demands on posterior teeth.
• Posterior movement: strategies impacted anchorage protection for premolars and molars, with implications for axial inclination and open bite tendency.
• Dispersed posterior movement increased anchorage load on the second premolar and mesial inclination.

Conclusions:

• The choice of anterior retraction method should consider stress distribution, individual patient factors, and clinical presentation.
• Posterior movement strategies must prioritize anchorage distribution and prevent posterior open bites.
• Incremental correction in smaller steps enhances axial control during clear aligner treatment.