Clinical Investigation Of Orthodontic Treatment Of Class Ⅱ Division 1 Malocclusion With Upper Jaw Extraction

Class n division 1 malocclusion is common in clinic. There are many methods for treatment, patients were treated with the extraction 4 premolars which needed to extraction. Patients couldn't accept the long treatment period and the number of extraction . The study was to investigate the indication and effects of orthodontic treatment with upper jaw extraction for Class II division 1 malocclusion. Methods19 patients with class II division 1 were extracted 2 first premolars or second premolars of upper jaw, 12 patients were extracted 4 premolars of upper and lower jaw. The investigation with cephalometric and cast records before and after were analysed by statistical methods . Results1 .After orthodontical treatment through 18 to 25 months (average 20.3 ?3.8 months), Molar relation is class II relation, cuspid relation is class I relation. SNA decreased 2.08 degree, the changes of SNB were unobvious, ANB decreased 1.85 degree. Ao-Bo decreased 2.29 mm. So sagittal relationship was significantly improved. Anterior facial height (N-Me) increased 6.12 mm and posterior facial height (S-Go) increased 3.97 mm, the ratio of facial height was 0.66 which approach the normal ratio. So vertical4relationship was improved.2.There were significant changes in dentition, the angle and distance of Ul-NA decreased 5.78 degree and 3.76mm;the Ll-MP angle increased 2.66 degree and the distance of Ll-NB increased 1.12mm;theUl-Ll angle increased 10.92 degree, overbite decreased 2.13mm, overjet decreased 5.06mm. There changes of maxillary incisor retraction were significant.3.The changes of soft tissue profiles were obvious , Z angle increased 4.67 degree, the nasolabial angle(Cm-Sn-Ls)increased 3.91 degree, the G-Sn-Pg' angle decreased 0.89 degree, the FH-N' Pg' angle decreased 0.77 degree ,the upper lip angle(LsSn-SN) decreased 6.09 degree, the Ls to E line decreased 3.08mm; the lower lip angle(LiSi-SN) increased 2.03 degree,the Li to E line decreased 0.54mm.The patients' profile was much improved.4.There were no changes in the Anterior ratio, the Over-all ratio approach the normal ratio 88% which was 88.76%. As a result of a good occlusion, the upper and lower tooth size is harmonious .5. The PAR scores and ratio decreased 17.83 and 83.08%,the weighted PAR total scores and ratio decreased 29.87 and 86.01%, the malocclusion was greatly improved. Conclusion:The orthodontic treatment of Class II division 1 malocclusion with upper jaw extraction which patients would accept the short treatment period and the number of extraction. The patients' profile was greatly improved; overjet and overbite approach the normal; good occlusal intercuspation is also achieved. The model of extraction is suitable for class II division 1 patients with mild or moderate skeletal and dental protrusion of mild crowding in mandible with less lower lip protrusion and less labial tipping lower incisor .