Tweed-Merrifield In Angle Class Ⅱ Division1Extraction Correction

Objective: Us the Tweed-Merrifield technique and discuss the extraction oftreating class II~1malocclusion.Materials and method: A male case with class II~1was selected from Dalian OrthoClinic in April2011,who was12years old,of Han nationality,Bilateral molar Class IIrelationship; Ⅰ°deep overbite、I°deep overjet; upper severe crowding、lower mildcrowding; tense muscles of the lower lip,the chimb of chin lip is deep.By clinicalexamination of the patient, the model analysis, cephalometric analysis, Tweedanalysis,extract the maxillary two first premolars and mandibular two secondpremolars,applied Tweed-Merrifield fixed technology, hard and soft tissuecephalometric changes was observed before and after treatment.Results: The course of orthodontic treatment is22months. Comparing the changesbetween treatment: analysis of comparative measurements: Bilateral upper and lowerdentition was neatly the normal overbite and normal overjet; the bilateral molarrelationships was neutral,cephalometric improved;FMIA increased2°,both FMA andIMPA decreased1°,SNA decreased1°,SNB increased1°, ANB decreased2°,AO-BOdecreased2mm, Z angle increased1°; facial profile was good; The patient and hisparents were satisfied with the result of the therapy after treatment.Conclusions：This case application Tweed-Merrifield technology,extract maxillaryfirst premolar and mandibular second premolar correcting class II~1malocclusion. theeffect is very significant.