How Predictable Is Invisalign First for Dental Arch Expansion?

When you plan expansion on the software, how much of it actually shows up in the mouth?

This is one of the most practical questions in clear aligner therapy, and a new systematic review and meta-analysis puts a number on it for Invisalign First in mixed dentition patients.

Maxillary arch constriction is common in mixed dentition and requires timely expansion to accommodate permanent teeth and prevent malocclusion. Clear aligners, including Invisalign First, offer an aesthetic alternative to conventional expansion appliances, but the predictability of dental expansion with clear aligners remains uncertain.

How Predictable Is Clear Aligner Expansion?

To address this issue, two researchers searched PubMed, Embase, Scopus, and Web of Science up to July 2025. From 53 records, nine studies were included in the review and eight in the meta-analysis, covering 349 children treated with Invisalign First.

Predictability, defined as achieved expansion divided by planned expansion, was pooled separately for the maxilla and mandible using a random-effects model. Risk of bias of the included studies was assessed with ROBINS-I.

Clear aligner treatment planning and biomechanics form an important part of modern orthodontic practice. LDI’s Postgraduate Diploma in Orthodontics & Dentofacial Orthopaedics includes clear aligner training using a brand-agnostic approach, alongside diagnosis, treatment planning, biomechanics and appliance selection.

How Much Planned Expansion Was Actually Achieved?

Overall, the predictability of expansion was 65% in the maxilla and 71% in the mandible, indicating that the achieved expansion was generally less than planned.

In the maxilla, predictability ranged from 58% for permanent first molars to 70% for deciduous canines, while the mandibular values were more consistent, ranging from 70% to 75% across different tooth regions.

The pattern points to biomechanics rather than anything specific to Invisalign First. Aligners expand teeth mainly by tipping the crowns rather than moving the roots bodily, and this limitation is most obvious at the posterior maxilla, where larger, multirooted molars with buccal tipping give the aligner less to hold onto.

Lower teeth tend to sit more lingually, so aligners seem to control them more reliably across the whole arch.

Importantly, the amount of planned expansion was not associated with predictability. Correlation and regression analyses found no relationship between planned expansion and accuracy achieved, suggesting that prescribing greater expansion in ClinCheck does not necessarily make the outcome less predictable.

What Does This Mean for Clinical Practice?

The key takeaway of this review is that Invisalign First is expected to deliver roughly two-thirds of planned expansion in the maxilla and about three-quarters in the mandible, with the upper permanent molars showing the least predictable movement.

Clinicians should therefore expect some degree of under-expansion, particularly in the posterior maxilla, rather than assuming that the planned expansion will be fully achieved.

The findings also reinforce the importance of understanding the biomechanics behind clear aligner treatment rather than relying on the digital treatment plan alone. Predicted movement on software does not necessarily translate directly into achieved clinical movement, particularly in areas where the underlying biomechanics make expansion less predictable.

Study Limitation

All nine studies were non-randomised, and most had a moderate risk of bias, limiting the generalizability of the findings. Variability measures were inconsistently reported, preventing meta-regression.

Read More

Serafin M, Boccalari E, Caprioglio A. Predictability of clear aligners in achieving planned dental arch expansion during mixed dentition: a systematic review and meta-analysis. Angle Orthod. 2026;96(4):469–481.

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