Factors affecting expansion predictability of clear aligner treatment

Area of Science:

• Orthodontics
• Dental Technology
• Biomaterials

Background:

• Clear aligners are increasingly used for orthodontic treatment.
• Predicting expansion with clear aligners is crucial for treatment success.

Purpose of the Study:

• To identify clinical factors influencing the predictability of dental arch expansion using clear aligners.
• To analyze the accuracy of predicted expansion versus achieved expansion.

Main Methods:

• Utilized digital cast data from 98 patients treated with Invisalign clear aligners.
• Measured arch width changes (canines, premolars, molars) from pretreatment and refinement digital models.
• Calculated expansion predictability and analyzed predictors using generalized linear mixed models (GLMM).

Main Results:

• The mean difference between planned and achieved expansion was 0.92 mm.
• Underexpansion occurred in 72.2% of measurements; overcorrections were more common in the mandible.
• Predictors of expansion predictability included arch, tooth type, amount of predicted expansion, and presence of posterior crossbite.

Conclusions:

• Clear aligner expansion is more reliable in the mandibular arch and canine region.
• Maxillary expansion, posterior teeth, and cases with existing posterior crossbite present a higher risk of unpredictability.
• Treatment planning should consider these factors for improved outcomes.