Innovative Maxillary Expansion Technique with Mini-Screw Supported Modified Hyrax Appliance

Objectives: The aim of this study was to analyze expansion pattern of maxillary dentition and skeleton with an innovative bone-borne maxillary expansion technique.

Methods: For a 26-year old male exhibited an anterior open bite with significant narrowness of maxillary arch a modified hyrax appliance was customized and attached to his palate with four 2mm-diameter and 10mm-length mini-screws. Four 1.4mm-diameter and 8mm-length mini-screws were placed in palate distal of canines and first molars as skeletal indices. A sub-Lefort I osteotomy was done under general anesthesia. After 7 days latency period expansion starts with rate of 0.8mm and rhythm of 2 times per day. Skeletal and dental changes were measured with cast analysis.

Results: These increases at transverse dimensions were obtained after 9.6mm hyrax expansion:

- 11.35mm at anterior skeletal indices

- 6.99mm at posterior skeletal indices

- 16.26mm diastema

- 14.61mm at inter-canine width

- 9.89mm at inter-molar width

Conclusion: This technique can be an effective therapeutic method for maxillary expansion and spares negative side effects of tooth-borne techniques.