EC Dental Science

Orthodontic treatment for severe narrowing of both the maxillary and mandibular dental arches often involves tooth extraction and interproximal reduction. To avoid these procedures, we performed skeletal expansion using dedicated expansion appliances. Although the Quad-Helix (QH) has long been used effectively for maxillary expansion, achieving substantial orthopedic effects with this appliance has generally been considered difficult. In this study, we developed a modified QH (TYO-QH) to maximize parallel expansion of the maxillary dental arch and correct asymmetry. For mandibular expansion, we used the Bio-Template, a screw-based appliance. This combined approach enabled semi-rapid asymmetric expansion and was associated with improvements not only in masticatory function but also in tongue function, swallowing function, nasal breathing, and postural habits. These findings suggest that the TYO-QH is effective for expansion of the maxillary complex and may broaden the possibilities of orthodontic treatment.

Keywords: Modified Quad-Helix; Maxillary Skeletal Expansion; Non-Extraction Orthodontic Treatment; Asymmetrical Cases; Semi-Rap- id Maxillary Expansion

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