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

The aim of the study was to evaluate the Skeletal, dentoalveolar and soft tissue factors underlying deep over bite malocclusions with comparison to normal occlusion by using cone beam tomography. A cross sectional observational study was performed on 80 subjects (40 deep bite, 40 normal occlusion) with age range 18 to 25 years. The inclusion criteria of deep bite group were, deep overbite more than 3 mm ({u2265}30% of labial surface of lower incisors overlapping), full permanent dentition with the exception of the third molar, no history of orthodontic treatment, absence of severe craniofacial disorders. In normal occlusion group the inclusion criteria were balanced facial proportions, coincidental facial and dental midlines, no previous orthodontic treatment, skeletal and dental class I, Intra arch crowding <2mm. Eighty CBCT images. Eighty CBCT images were converted to DICOM format with i-CAT unit. By using the Anatomage (image processing software version 5.0), fully reconstructed 3D volumetric images were generated. All Landmarks were located on the 3D volumetric images and refinement of landmark localization was performed by using the generated multi-planar slice locator in the three planes of space (sagittal, coronal and axial cuts). Deep bite showed lower values regarding ramus length, GO-GO, J-J, Zy-Zy and MF-MF distance, upper incisor inclination, maxillary posterior alveolar height, vermillion height and lower lip length. Deep bite showed higher value regarding inter incisal angle, overjet, curve of spee, labrale inferius to E line and lower lip thickness. The most skeletal contributing factors of deep bite was decreased ramus length, decreased maxillary width, facial width and mandibular width. The most dentoalveolar contributing factors of deep bite was increased curve of spee, decreased the maxillary posterior alveolar height, decreased inclination of upper incisors and higher value of inter incisal angle. In soft tissue the deep bite group showed decreased vermillion border height and lower lip length but there was increased labrale inferius to E line and lower lip thickness

Issued also as CD