الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The significance of the occlusal plane is emphasized by many publications within literatures. The occlusal plane affects the position of mandible, smile esthetics, masticatory function and stability post-orthodontic treatment. A relationship exists between occlusal plane inclination and various skeletal profiles: Class II malocclusion has steeper occlusal planes whereas Class III malocclusion has flatter occlusal planes. Also, the occlusal plane inclination varies relative to vertical jaw discrepancies, steeper occlusal plane inclinations were found to be associated with the hyper-divergent individuals, and flatter occlusal plane inclinations were associated with the hypo-divergent individuals. The occlusal plane plays an important role in many aspects of orthodontics. During orthodontic treatment, the occlusal plane is modified to achieve stability of occlusion after treatment. Therefore, this study was performed to assess the occlusal plane inclination of both AOP and POP in different skeletal patterns and vertical facial patterns. The sample involved in this study included lateral cephalometric radiographs of 180 adults Egyptian Orthodontic patients of both males and females of different skeletal malocclusion pattern who attended treatment at the Orthodontic department at the Faculty of Dentistry, Tanta University All lateral cephalometric radiographs collected were coded, traced accurately and cephalometric landmarks were defined and plotted on each radiograph. Subjects were then allocated into the three defined groups of malocclusion: Class I, Class II, and Class III based on the ANB angulation according to the cephalometric norms for the Egyptian Population published by Aboulazm et al (73), then a group of cephalometric angular measurements was obtained and tabulated from the traced cephalometric radiographs of all the groups of malocclusion. A two-way analysis of variance (ANOVA) was carried out to compare the different occlusal planes and its relation for both horizontal and vertical skeletal pattern.. All statistical analysis was performed using SPSS for Windows, Version 25.0. The results had shown that the skeletal patterns had a statistically significant difference in the AOP angle in both SN plane and FH plane among the three malocclusion patterns (p-value =0.000**) showing a steep inclines plane in Class II and flat inclines plane in Class III. While no significant difference was found in any of the POP angles to SN (p=0.014*) and FH (p=0.217) among the three malocclusion groups. As for the vertical pattern, it showed a significant difference in both AOP and POP relative to both SN plane and FH plane (P=0.000**) among the three vertical pattern groups showing a steep incline in the high angle group and flat incline plane in low angle group .