Immediate Effect of the Twin Block in the Airway on Patients with Class II Div 1 Malocclusion

Background: there is a relationship between the mode of breathing and antero-posterior jaw relation. Severe mandibular deficiency has been linked to reduced oro-pharyngeal airway dimension (OAW). Dental literature reported many studies on functional appliances and their effects, but there are few published studies on their effects on the airway. Design: prospective analytical (comparative) study. Setting: orthodontic clinics at university of Khartoum and university of Science and Technology. Objectives: to investigate the immediate effect of the Twin block (TB) functional appliance in the airway on patients with class II division1 (div1) malocclusion and to measure the immediate changes in the position of the hyoid bone after insertion of the TB appliance. Materials and Methods: two lateral cephalometric radiographs were taken and analyzed one before and second after insertion of the TB appliance for the 19 patients with class II div1 malocclusion. The age range was 10-14years. Immediate change in the airway was performed by measuring the change in the vertical position of the hyoid bone relative to the mandibular plane (H1) and to the (cv3-RGN) plane (H2). The change in the airway can be measured by the change in the vertical position of the hyoid bone before and after insertion of TB appliance (H1+H2). Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. x Results: the hyoid bone changes in a more superior position after the insertion of the TB appliance. The mean of the change was 11.8mm, with SD 2.8mm (p=0.0001) at 0.01% level. Conclusion: the vertical hyoid bone position was changed in amore superior position immediately after the insertion of the TB appliance on patients with class II div1 malocclusion. Further, the TB has an immediate positive effect in the airwa