| Object:This study was designed to observe and evaluate the clinic effect of the dual-phase treatment in skeletal ClassⅢmalocclusion.Methods:A male case with skeletal ClassⅢmalocclusion.was selected from The first Affiliated Hospital of Dalian Medical University ortho clinic in 2008,who was 10 years and 9 months.Clinical examination display maxillary deficiency with a lightly protruded mandible,bilateral molars ClassⅢrelationship, 2-mm negative overjet,2-mm deviation of the mandibular midline to the right,a concave profile appearance. His mandible could move into edge-to-edge anterior occlusion.Treat the patient with 2 phases:phaseⅠof the orthopedic therapy with a rapid palatal expander and a maxillary protraction;phaseⅡusing the straightwire appliance.Compared and analysed the lateral cephalometric radiograph and plaster modle among the pre-treatment,the end of therapy phaseⅠand after treatment.Result:The course of orthodontical treatment needs 32 months. Compare the changes between pre-treatment and protreatment:After the phaseⅠtreatment,the first molar relationship changed from ClassⅢinto l,the anterior crossbite had been corrected and the maxillary dental arch was expanded,skeletal facial profile was improved.SNA angle increased 4o,Naperp.-A increased from -5 to 1.5,SNB did not significantly ANB increased from -5 to -2.5,U1/SN increased from 115o to 125o.phasesⅡstrengthen the effect of phasesⅠ.compared with phasesⅠ,SNA angle increased 3°,ANB angle increased 5.5o,while U1/SN angle decreased to 22o,L1/MP increased 3°,the values are close to normal.The vertical analysis indicates that,MP/SN angle increased 1°,face height ration did not increase.maxillary soft tissue profile improved,the patiention and his parents were satisfied with the result of ortho therapy after treatment.Conclude:maxillary protraction therapy can provides effective correction in early class III malocclusion,with the straight wire appliance,the treatment could achieve a better clinical result. |
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