الفهرس 
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Abstract
Maxillary transverse deficiency in adults is a debated topic as regards the most suitable method of treatment. Orthodontic maxillary expansion has been used by orthodontists as the best treatment option, but adverse effects on the teeth and bone have been proven. Surgically assisted rapid maxillary expansion was found to be less damaging to dentoalveolar structures in adult patients requiring maxillary expansion. The aim of this study was to compare the effects of tooth-borne and bone-borne surgically assisted rapid maxillary expansion using the tri-partite osteotomy surgical technique. CBCT images were used to evaluate the difference between two different orthodontic appliances; the Hyrax appliance and Transpalatal Distractor.
A sample of 24 adult subjects that required surgically assisted maxillary expansion was selected from the outpatient clinic of the Orthodontic Department in the Faculty of Dentistry, Ain Shams University. The patients were divided into 2 groups randomly. The first group were 12 patients who received Hyrax appliance while the second group were also 12 and received bone-borne Transpalatal Distractor. Three patients were lost in the first group and four patients were lost in the second group. The final sample included 9 patients in group I and 8 patients in group II.
After taking the standard orthodontic records and discussing the treatment plan with the patint the Hyrax appliance was constructed for the first group and the Transpaltal distractor of the proper size was selected for patients in the second group. The surgery was carried on under general anesthesia and involved tripartite osteotomies where the surgical cuts were between the lateral incisor and canine bilaterally. The latency period ranged from 2-5 days then the patients or a family member were taught how to activate the device and were asked to activate the device two turns per day (0.25 mm per turn); equivalent to a rate of 0.5 mm/day. No life-threatening complications occurred in the postoperative phase and all patients tolerated the surgery well.
Expansion was continued till the palatal cusps of the maxillary posterior teeth come in contact with the buccal cusps and the end point of the expansion was when overcorrection was achieved. The device was left for a consolidation period of 4-6 months. No orthodontic forces were applied to the teeth during this retention period in order to compare the effects of the Hyrax and the Transpalatal distractor.
Summary
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Each patient received a cone beam computed tomography (CBCT) using iCAT CBCT scanner before the beginning of treatment, and after six months of the expansion procedure. DICOM images were imported in the inVivo anatomage software.
Different skeletal dentoalveolar as well as soft tissue measurements were carried out to evaluate the effects of both appliances with the relatively new surgical techniques. These measurements were statistically analyzed, and the results of the study were obtained.