الفهرس 
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Abstract
Rapid maxillary expansion has been the treatment of choice for most skeletal maxillary transverse deficiency, however, there is a general consensus regarding at what age limit this is applicable without surgical intervention. Integrating miniscrews in the expansion appliances creating what is termed the “hybrid” expansion device, has made this expansion procedure to be carried out in older age groups without the need for invasive surgical procedures, and has allowed for a qualitatively better expansion than the traditional tooth-borne expansion devices.
Eighteen patients in the late adolescence stage were randomly divided into two groups; one group was treated with the conventional expansion “Hyrax” device, and the other with the “Hybrid” expansion device with two miniscrews places in the palate with monocortical engagement. Both groups followed the same device activation protocol.
Cone beam computerized tomography scans were taken before and after the expansion treatment and compared on several dental, dentoalveolar and skeletal parameters.
The data that was collected from the pre-treatment and post-treatment scan were statistically analyzed for the changes that had occurred and the differences between both groups were compared.
The results showed that the patients treated with the conventional Hyrax in this age group showed greater -though mostly statistically insignificant- results across most parameters, however, those results were unfavorable as they were mostly dental than they were skeletal and came at the expense of the dentoalveolar condition.
The patients treated with the Hybrid device showed comparable expansion results but with more favorable characteristics. This includes the more parallel separation pattern of the maxillary halves and the lesser amount of dental tipping with less buccal alveolar affection.