Effects of Modified Fixed Twin Block Versus Removable Twin Block on Skeletal Class 2 Growing Patients With Mandibular Deficiency

The main objective of the study is to evaluate the effects of the modified fixed TB on class 2 growing cases and to compare its effect to the conventional removable TB Research question Does the modified fixed twin block have the same effects as removable twin block during treatment of skeletal class 2 growing patients with mandibular deficiency? PICO P: Growing skeletal class 2 patients with deficient mandible I : Modified Fixed Twin block C: Conventional removable Twin block O : Primary outcome: Overjet Secondary outcome: Soft tissue Profile Antro-posterior mandibular position Mandibular length Antro-posterior maxillary position Upper and lower Incisors inclinations Durability of the appliance Patient Acceptance Hypothesis: There is no difference between the modified fixed or removable Twin block appliance regarding overjet reduction, dentoskeletal effects and patient perception. 8\. Trial design: Randomized Clinical Trial Parallel group, two arm, equivalent trial with 1:1 allocation ratio.