The Different Methods For The Early Treatment Of Angle Class Ⅱ Division 1 Malocclusion: A Cephalometric Study

Objective: To investigate the treatment effects on skeletal,dental and facial changes by functional and fixed appliances at the peak stage of development, and provide theoretical basis for the clinical therapy in class II division 1 malocclusion.Method: The research consisted of the 30 patients with skeletal class II division 1 malocclusion, which in the age of 11 to 14 years old were divided into two groups. One group was treated for 16 months by standard Edgewise appliance (E group), the other was treated by Twin-block functional appliance (T group) ,whose active treatment and rentention time was 16 months too. The cephalometric data before and after treatment as well as the cephalometric data of two treated groups and control were analysed statistically.Result:1. After fixed treatment, the mandibule did not change significantly in the sagittal direction: SNB drgree, mandibular body length(Go-Gn), the distance from B, Pg to FHp plane were not statistically significant before and after treatment. Skeletal relation (ANB degree) and fullsoft tissue convexity (N'-Pn-Pg' degree) were not statistically significant too. Overbite, overjet and molar relation changed significantly(p<0.05), which decreased after treatment . The overjet decreased by 4.4mm on everage, of which skeletal changes were zero and 100 percent was due to dental changes. Class II molar correction averaged 2.3mm, for which dental changes accounted 100 percent while skeletal changes for none.2. The structure after fixed treatment compared with control showed significantly different (p<0.05) in sagittal and vertical direction of mandibule: body length(Go-Gn), the ramus height(Ar-Go), the mandibular length(Ar-Pg), SNB degree. Skeletal relation (ANB degree) and full soft tissue convexity (N'-Pn-Pg' degree) were different too. The cephalometric value in fixed group was lower than that of normal group except ANB degree.3. After functional treatment, the mandibular changed significantly in the sagittal and vertical direction: SNB drgree, mandibular body length(Go-Gn), the ramus height(Ar-Go), the mandibular length(Ar-Pg), the distance from B, Pg to FHp plane were statistically significant before and after treatment (p<0.05), which increased after treatment. Skeletal relation (ANB degree) and full soft tissue convexity(N'-Pn-Pg' degree) were statistically significant too(p<0.05). N'-Pn-Pg'degree increased after treatment, and ANB degree decreased. Overbite, overjetand molar relation changed significantly(p<0.05), which decreased after treatment . Overjet correction averaged 5.9mm, of which 61 percent was due to dental and 39 percent due to skeletal changes. Class II molar correction averaged 6.0mm , of which 60 percent was due to dental changes and skeletal changes was 40 percent. 4. There were no significantly difference in sagittal and vertical direction of mandibule , the relation of skeletal and soft tissue between post-functional treatment group and normal group . Conclusion:1. Functional treatment for correction of class II occlusion is achieved mainly by the skeletal and little by dental changes. Functional treatment can promote mandibular growth obviously, increase mandibular length in sagittal direction and mandibular height in vertical direction and improve the class II profile effctively, and the skeletal relation and soft tissue profile become normal after treatment.2. Fixed appliance in the treatment of class II occlusion functions by the dental change completely, the relation of skeletal and the class II profile are not improved.3. It's advisable to treat class II division 1 malocclusion with functional appliance at the peak stage of growth and development, and improve occlusion relation with fixed appliance at the second stage.4. The fixed treatment can be used directly in the class II division 1 malocclusion when patient's profile is similar to class 1.