Letters From Our Readers

To Editor, The Angle Orthodontist

Re: Vertical and transverse treatment effects of Invisalign First system compared to Hyrax maxillary expanders with fixed appliances in mixed dentition patients. Parisa Moravedje Torbaty; Heeyeon Suh; Sandra Khong Tai; Marta Baird; Robert L. Boyd; Heesoo Oh. The Angle Orthodontist. 2024;94:496–503.

We appreciate the extensive work of the authors on this evolving topic. We wish to ask the authors to clarify the reason that patients in the study were undergoing an expansion procedure. Since bilateral posterior crossbite was one of the exclusion criteria for patients in the study, can you please describe more precisely the indications for expansion performed in the Invisalign First and Hyrax groups if it was not done to correct bilateral crossbite? How many of the patients in each group, for example, had unilateral crossbite or were just undergoing expansion to resolve arch length deficiency? Additionally, it might be helpful to include pre-treatment or post-treatment images of a patient in each group.

Thank you for considering our questions and providing more information on this topic.