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Maxillary expander with differential opening vs Hyrax expander: A randomized clinical trial
Arthur César de Medeiros Alves1, Guilherme Janson1, James A Mcnamara2
1Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
Summary
The expander with differential opening (EDO) promotes greater anterior maxillary expansion than the Hyrax expander in children with constricted arches. Both devices showed similar effects on posterior arch dimensions and palatal depth.
Area of Science:
- Orthodontics
- Craniofacial Development
- Dental Arch Expansion
Background:
- Maxillary arch constriction is a common orthodontic concern in the mixed dentition.
- Orthopedic expansion aims to correct transverse discrepancies and improve arch form.
Purpose of the Study:
- To compare the dentoskeletal effects of the expander with differential opening (EDO) and the conventional Hyrax expander.
- To evaluate differences in midpalatal suture opening, arch dimensions, and tooth inclination.
Main Methods:
- A 2-arm parallel trial randomized 46 patients (aged 7-11 years) into EDO and Hyrax groups.
- Standardized activation protocols were followed for both expanders.
- Dentoskeletal outcomes were assessed using occlusal radiographs, intraoral photographs, and digital dental models.
Main Results:
- The EDO group demonstrated significantly greater anterior midpalatal suture opening and interincisive diastema increase.
- EDO achieved differential expansion between anterior and posterior regions, unlike the Hyrax expander.
- No serious harm was reported in either group.
Conclusions:
- The EDO is more effective in promoting anterior orthopedic and dental changes in the maxilla compared to the Hyrax expander.
- Both expanders yielded similar results for posterior arch width, perimeter, length, palatal depth, and posterior tooth inclination.
