Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

This study was carried out to investigate, using cone beam computed tomography (CBCT) imaging, the ideal position and angulations for mini-screws insertion in the mandibular posterior area either vertically or horizontally. This study was carried out on 30 patients radiographic CBCT that were selected from an already available larger sample of images at the database of a radiological center for the purpose of evaluation. Every x-ray was evaluated in both right and left mandibular sides separately. For each subject the selected CBCT assessed bilaterally in two different areas: 1.External oblique ridge area : For vertical mini-screws placement distal and opposite to mandibular second molars. 2.Mandibular interradicular spaces: For horizontal mini-screws placement between first and second molar and between second premolar and first molar. By comparing different sites and angulationsthe following conclusions could be drawn: a)For vertical mini-screws (in external oblique ridge) : 1.When the mini-screws insertion angle is parallel to the long axis of the tooth, it offers more available bone length. 2.When the point of insertion moves distally, it offers more available bone length. b)For horizontal mini-screws (in interradicular spaces): The more distal the insertion site is, the more it offers bone length for mini-screws. c)Vertical mini-screws offer a more available bone length than horizontal mini-screws. d)There is no statistical difference between the right and left sides in available bone length

Issued also as CD