Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

Introduction: Forsus fatigue resistant device (FFRD) was reported to be successful in the correction of Class II division 1 malocclusion. Dento-alveolar changes were stated to be the main component of this correction. Objective: To detect the three dimensional effects of FFRD and the efficiency of direct mini plates anchorage in minimizing the dento-alveolar side effects and increasing the skeletal effects of the appliance therapy. Methods: A sample of 34 skeletal Class II females with deficient mandibles were randomly allocated into two groups; 17 patients (12.08±0.8 years) received FFRD and miniplates in the mandibular symphysis (treatment group), and 17 untreated Class II subjects (11.98±0.9 years). CBCT radiographs were taken before insertion and after the appliance removal. Three dimensional analysis was used including skeletal, dento-alveolar and soft tissue measurements. Statistical tests were used to compare between changes among the groups. Results: Class I canine relationship and overjet correction were achieved. The use of miniplates in conjunction with FFRD resulted in significant increase in the effective Amandibular length as compared with the control group. The dental effects comprised retroclination and extrusion of maxillary incisors, distalization of maxillary molars and extrusion of mandibular molars. Retroclination and extrusion of mandibular incisors were significantly greater in the miniplates group. Conclusion: The addition of the miniplates to the FFRD was successful in enhancement of the skeletal treatment outcomes in Class II division 1 malocclusion. Unfavorable proclination and intrusion of mandibular incisors was effectively eliminated with the utilization of direct miniplates anchorage

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