Clinical Research Of Mandibular Protrusion Appliance Therapy On Patients With Class Ⅱ Division 1 Malocclusion And Mandibular Retrusion

Class â…¡ division 1 malocclusion with mandibular retrognathia is common in orthodontic clinic. To treat this kind of malocclusion, the molar relationship must be modified and concomitant deepbite and overjet must be corrected. A removable functional appliance can be used for this purpose.The traditional functional appliances are so big and uncomfortable that patients dislike wearing , so the success of removable functional appliance therapy is strongly dependent upon patient's good cooperation. More and more orthodontists prefer to use those fixed functional appliances that can be combined with fixed appliances.Mandibular protrusion appliance was modified from Herbst appliance, this study was to investigate the effects of mandibular protrusion appliance combined with Edgewise fixed appliance on juveniles with class â…¡ division 1 mandibular retrusion problems.Methods:23 patients with Class â…¡ division 1 mandibular retrusion problems were treated by using mandibular protrusion appliances for6-8 months (average7.2 months).Mandibular protrusion appliances were fixed after dentition alignment. Cepholometric roenteno-grams and TMJ lateral tomograms were made before fixation and removal of the mandibular protrusion appliances .The results were evaluated with cepholometric analyses.Results:Changes of hard and soft tissues after treating with Mandibular protrusion appliance in growing children with Angle class II division 1 malocclusion and mandibular retrusion are as following:1. Changes of jaw growth Compared with pretreatment,SNA was not decreased significantly after treatment;SNB was increased significantly about 4.62 degree; mandible length(Go-Gn), both of anterior and posterior facial hight were increased significantly.2. Changes of sagital and vertical relationship of jaws ANB was decreased significantly about 3.63 degree; facial hight index was decreased significantly;overbite was decreased significantly about 4.74mm and overjet was decreased significantly about 2.24mm.3. Changes of mandible rotation GoGn-SN and Gonial angles were not changed significantly.4. Changes of soft tissues Soft tissues were changed significantly with hard tissues, SN'Si increased 2.63 degrees, LiSi-SN' was increased 17.28 degrees, Si-E was decreased 2.08 mm, so patients' lateral profiles were improved.5. Changes of tepromandibular The condyle was nearly in the middle of glenoid fossa,but slightly forward before the fixation of mandibular protrusion appliance, and was moved forward and downward obviously after the fixation of mandibular protrusion...