| Objective: To investigate craniofacial changes in hard tissue of class Ⅱ division1using Tweed-Merrifield directional force technology.Materials and Method: A case with class Ⅱ division1malocclusion wasselected from Dalian Ortho clinic in2012, who was a male,11.7years old, with normalmaxilla, recessive mandible, chin underdevelopment and high angle. Deep overjet ofanterior teeth:7mm, bilateral molars class Ⅱ relationship, mild crowed of upper arch.Midline of lower arch is the same with the upper arch. Take X-ray lateral radiographicfilms pre-and post-treatment in seven days.29hard and soft tissue marked points ofcephalometric radiographs were drawn in a period time. There were25typicalmeasurements were selected from Tweed analysis and so on, so as to observe thechanges between sagittal and vertical dimension from pre-and post-treatment.After analyze the X-ray of the patient. The patient was extracted the stranded milkteeth, four first premolars maxillary and mandibular with Tweed-Merrifield technology.Results: The course of orthodontic treatment is22months. Comparing thechanges between pre-treatment and post-treatment: the molar relationship was changedto class Ⅰ. Root resorption of maxillary incisors and lateral incisors not seen. Tooth axis was good. The overjet is4mm now. SNA increased3°.SNB increased1°. ANBincreased2°.NA-PA increased5°.FMA decreased2°. It explained that there is awonderful vertical control. Z angle has risen from49°to60°。The soft tissue profileshowed improvement. The patient and his parents were satisfied with the result afterorthodontic treatment.Conclusions: Skeletal Class Ⅱ division1malocclusion in early permanentdentition can be treated successfully by Tweed-Merrifield directional force technologywith extraction four first premolars. The results can be satisfied from the improved:class Ⅱ skeletal and molar relationship, deep overjet and profile of soft tissue. |
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