This research was carried out to compares the treatment effects of Horizontal and Vertical type activators in Angle's Class II div. 1 maloccusion patients with mandibular retrusion dand to find out whether different treatment effects or growth pattern were observed between sexes in each study groups. The results were as follows: 1. In Horizontal activator group, forward positioning of mandible and vertical increase in anteror face as examplified by increase of LAFH and AFH were observed when pre and post-treatment datas were evaluated. 2. Males samples in Horizontal activator group showed increase in mandiular length accmpanied by posterior positioning of maxilla, wheras female samples in Horizontal activator group showed increase in mandibular body length,labial inclination of mandibular incisors and increase in lower anterior facial height . 3. In vertical activator group, increase in AFH, LAFH, PFH and LPFH were observed when pre and post treatment datas were a aluated. 4. Male samples in Vertical activator group showed increase in mandibular body length and anterior and posterior facial heights, whereas females samples of Vertical activator group showed mainly increase in anterior facial height 5. When pre and post treatment datas of Horizontal and Vertical activator groups were compared, skeletal difference were mainly observed in eatrnnt datas but dental difference were observed in post treatment datas ,indicating that two actiators differ only in their effects to dental variables. 6. Difference between sexes were noted after treatment although no difference were observed between sexs in each groups before treatment This indicates that inherent growth effects in each sex exerts more influence than appliances used for treatment.
Female ; Humans ; Incisor ; Male ; Malocclusion* ; Mandible ; Maxilla ; Retrognathia

Since the finite element method(FEM) was introduced to the orthopaedic biomechanics, it has been applied with increasing intrest to investigate bone, bone-prosthesis, and fracture fixation device, etc., in terms of stress, strain, force, and displacement. The authors implemented the FEM for the "intact" and the "fractured long bone models respectively to observe the mechanical behaviors of the plate fixation for the long bone fractures, and we observed the followings;l. In the intact model, stresses are evenly distributed and smoothly changed. 2. The maximum equivalent von-Mises stress in the fracture model is higher than that in the intact one. 3. Stresses on the plate are much higher than those on the bony surface in the fracture model. 4. Stresses for the bony surface beneath the plate in the fracture model are much lower than those in the intact model;however, stresses are highly concentrated around the screws. 5. Although two-thirds of total compressive load is transmitted through the fracture site area, maximum von-Mises stress in the fracture site is much lower than that in the plate. 6. High stresses are found at the areas between the plate holes and the screw heads. 7. Shearing forces of the screws are higher at the near and end screws from the fracture site.
Fracture Fixation ; Fractures, Bone ; Head