Evaluation of dimensional changes in dental arches after maxillary expansion: a comparative study between Invisalign® first and Hyrax appliances in the mixed dentition

Authors

  • Ana Cláudia de Castro Ferreira Conti Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Odontopediatria, Ortodontia e Saúde Coletiva.
  • Victor de Miranda Ladewig University of Alberta. Edmonton Clinic Health Academy. Mike Petryk School of Dentistry.
  • Gabriela Utrago Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Odontopediatria, Ortodontia e Saúde Coletiva.
  • Paula Vanessa Pedron Oltramari Universidade para o Desenvolvimento do Estado e da Região do Pantanal (UNIDERP). Departamento de Ortodontia.
  • Renata Rodrigues de Almeida-Pedrin Universidade para o Desenvolvimento do Estado e da Região do Pantanal (UNIDERP). Departamento de Ortodontia.
  • Thais Maria Freire Fernandes Universidade para o Desenvolvimento do Estado e da Região do Pantanal (UNIDERP). Departamento de Ortodontia.

DOI:

https://doi.org/10.1590/1678-7765-2025-0815

Keywords:

Removable orthodontic appliance, Palatal expansion technique, Aligners, Orthodontics

Abstract

Objective  This clinical study aimed to compare the outcomes of maxillary expansion using Invisalign® aligners and hyrax expanders in mixed dentition. Methodology  Overall, 35 patients (8.99±1.52 years, 17 males and 18 females) were divided into two groups: patients treated with dentoalveolar expansion appliance using Invisalign® First (IF group, 8.06±0.78 years, 9 males and 5 females) and patients treated with rapid maxillary expansion (RME group, 9.61±1.59 years, 8 males and 13 females). The treatment protocol was the same for all individuals within the same group. Digital dental models were analyzed at pre- (T0) and post-treatment (T1). The mean treatment duration was six months for the RME group and eight months for the IF one. Furthermore, the outcomes were compared to what was planned for the IF group. Arch dimensions were evaluated using digital dental models on OrthoViewer (3Shape, Copenhagen, Denmark). Intergroup comparisons were performed using the Student’s t- or Mann-Whitney tests. Intragroup comparisons were made by the paired t-test. All statistical analyses were performed with a 5% significance level. Results  A statistically greater increase in all transverse widths in the cervical points was observed in the RME group. The same result was found for the distance between the cusp tips of permanent first molars. Conclusions  Hyrax appliances promoted greater transverse expansion than Invisalign® First in all evaluated regions. Invisalign® First showed greater dentoalveolar effects, with the highest transverse gain observed in the deciduous second molar region and greater discrepancy between cervical and cusp tip measurements.

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Published

2026-11-09

Issue

Vol. 34 (2026)

Section

Original Articles

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How to Cite

Conti, A. C. de C. F., Ladewig, V. de M., Utrago, G., Oltramari, P. V. P., Almeida-Pedrin, R. R. de, & Fernandes, T. M. F. (2026). Evaluation of dimensional changes in dental arches after maxillary expansion: a comparative study between Invisalign® first and Hyrax appliances in the mixed dentition. Journal of Applied Oral Science, 34, e20250815. https://doi.org/10.1590/1678-7765-2025-0815