| Objective:To discuss the control of anterior teeth torque of bimaxillary protrusion with Tweed-Merrifield technology.Materials and methods:A 13 years old female patient with bimaxillary protrusion was selected from Dalian Ortho Clinic in 2013.The patient had Class I skeletal relationship with facial asymmetry and anterior dental protrusion.She was in permanent dentition stage with a Class III molar relationship,moderate crowding,normal overjet and overbite.In order to control the torque of the anterior teeth effectively,We extracted her four first premolars and two third molars and treated her with Tweed-Merrifield technique with headgear and J-hook.Results:The course of orthodontic treatment was 25 months.After the treatment,the patient had a better facial profile and Class I molar relationship.Cephalometric data shows great improvement in upper and lower incisors following orthodontic treatment : U1-NA changed from 30.5°to 26°,U1-SN from 118°to 114°,IMPA from 97°to 87°and U1-L1 from 114°to 129°.FMIA increased to 66°and Z-Angle to 68°,this indicates substantial improvement in soft tissue profile.Upper Lip increased to 13 mm,Total Chin to 12 mm,showing a 1:1 ratio.The more coordinated the Chin and lip proportion,the more esthetic and balanced facial results we got.Conclusion:With the use of high pull J hook headgear in Tweed-Merrifield technology,we can efficiently control the torque of anterior teeth. |
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