Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

Introduction: Bone- borne expanders are believed overcome the limitations of traditional tooth-anchored RPE. The aim of this 4-arm parallel randomized controlled clinical trial is to evaluate and compare the effects of bone borne RPE in pre and post-pubertal patients as well as to their matching control groups. Methods: The study included 44 subjects of both sexes with skeletal maxillary constriction. The treatment groups received a 7mm hyrax screw anchored to four palatal miniscrews. Photographs, models and CBCT images for all patients were collected before expansion (T1) and 5 months after (T2).Outcomes: The primary outcome of this study was to assess correction of the posterior crossbite by measuring the maxillary width changes at 3 levels. Secondary outcomes included evaluation of maxillary cant, orbital and nasal width, transverse and vertical dental changes and finally skeletal vertical and anteroposterior changes. Randomization: Computer number sequence generation was obtained using Microsoft Office Excel 2007. Allocation concealment was achieved with sequentially numbered opaque sealed envelopes. Blinding: Blinding of the clinicians and the patients to the intervention was impossible. The investigator was only blinded to group allocation at the level of data entry and measurement. The statistician was blinded as well

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