الفهرس 
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Abstract
A 3D finite element analysis study was carried out to evaluate stress distribution in the mandible produced from different types of space gaining techniques: teeth supported and tissue- teeth supported devices.
The analytical model was selected and scanned by CT scanner to get the ideal geometrical outline. Mimics software program was used to edit and crop the CT images. Three dimensional drawing of the model components was done by tracing every CT cut in Solidwork software program to produce a 3D model of the mandible. 3D model of teeth was obtained from printing and positioning the teeth according to the ideal angulations and inclinations of every tooth. The components of every expander appliance were also drawn according to manufacture description.
Assembling of different components with each other “bone and teeth, band and rod, acrylic body and anchorage clasps” were carried out to collect all parts of each model. The material properties for bone, titanium alloy, stainless steel alloy, acrylic, teeth and ligaments were identified. Load was applied in the two models according to ideal direction and magnitude.
The model was restrained at the condaylar neck to avoid total body displacement. The models were meshed with a curved based solid mesh and the analysis conducted with the iteration method. The stresses, displacement and safety factor at bone, teeth, and PDL were calculated. The results were collected and a correlation analysis test was performed. The results have shown that, the gerber space regainer and sagittal molar distalizer showed equal performance, with slight more effectiveness and safety by using sagittal distalizer.