The Analysis Of Efficancy Pre-and Post-treatment Of Class Ⅱ Division 1 With Edgewise Appliance

Objective: To investigate dental and craniofacial changes in soft and hard tissue of classⅡdivision 1 in early permanent dentition after orthodontic extraction treatment, so as to study the treatment mechanism of that malocclusion with edgewise appliance.Materials and method: A female case with classⅡdivision 1 high-angle skeletal malocclusion was selected from DaLian Ortho clinic in 2005, who was 10.3 years old, normal maxilla and recessive mandible, deep overjet of anterior teeth:8mm, bilateral molars classⅡrelationship,moderate crowed of upper arch and severe crowed of lower arch ,midline of lower arch 2mm left deviation. Uptake x-ray lateral radiographic films pre- and post-treatment in a month. 39 hard and soft tissue marked points of cephlometric radiographs were drawed in a period time. 28 typical measurements were selected from Beijing Medical University, Tweed,Wits and Wylie analysis, so as to observe the changes between sagittal and vertical dimension from pre- and post-treatment.The patient was extracted four first premolars maxillary and mandibular with edgewise appliance. Using high-pull headgear and face bow to reinforce the maxillary first molar anchorage, and using two-step to close the extraction space.Results: The course of orthodontical treatment is 22 months. Compared the changes between pre- and post-treatment: Molar relationship changed from classⅡinto classⅠrelationship. ClassⅡskeletal facial profile was improved: SNA decreased 0.5 degree, SNB increased 2 degree, so ANB decreased 2.5 degree. Overjet decreased 4mm. The retraction of anterior teeth was obvious. There were significant changes in dentition, the angle of U1/NA decreased from 33.4°to 22.0°, the distance of U1-NA decreased from 8.0mm to 3.5mm. The L1/MP angle decrease from 97°to 87°. The distance of L1-NB decreased from 9.5mm to 7.5mm. The angle of U1/L1 increased from103.0°to 128.0°. The vertical relationship was improved. The angle of MP/SN decreased from 45.0°to 40.9°. The percent of S-GO/ N-Me increased from 55.9% to 60.2%.The mandibular plane was slightly counterclockwise rotation; The profile of soft tissue improved significantly, which changed from convex surface type tending to directly facing type. The Z angle increased from 61°to 70°. The distance of Li-E decreased from 5.5mm to 2.0mm, and the distance of Ui-E decreased from 4.5mm to 0.9mm. The patient and her parents were satisfied with the result of orthotherapy after treatment.Conclusions: Skeletal ClassⅡdivision 1 malocclusion high-angle with moderate crowed of upper and lower arch in early permanent dentition can be treated successfully by edgewise appliance with extraction four first bicuspids. The results can be satisfied from the improved: classⅡskeletal and molar relationship, deep overjet, high-angle and profile of soft tissue.