| OBJECTIVE: Through comparative analysis of the changes of soft tissue profile and relevant hard tissue after the use of extraoral arch for the treatment of molar distalization in adolescent skeletal classⅡ, the paper discusses the specific indexes which affects the soft tissue and relevant hard tissue before and after the treatment.METHODS: Based on collecting and organizing 59 patients’ data that have applied the extraoral arch combined with fixed appliance for the orthodontic treatment in Orthodontics Department of Shenyang Stomatology Hospital during the period from January 2010 to December 2013, the paper selects 10 eligible cases to have a retrospective study. Inclusion Criteria: Late mixed dentition or early permanent dentition, skeletal classⅡrelationship, Ⅱmolar relationship, light and moderate crowding dentition, angle. They also suffered from the problems of the second permanent molar of maxillary that was not adorable out or built occlusal, and of high level treatment compliance of non-extraction borderline cases in their growth peak. Among these 10 patients, 3 were male and 7 were female, their average age was 12(age range: 10 to 14), their nationality was Han Chinese. By the means of measuring and analyzing the relevant statistics of cephalometric X-ray positionings of patients before and after correcting, the paper made a study statistically, which included the measurement and comparative analysis of the indexes of major soft tissues before and after correction, these tissues were: CmSnLs, SnLs-Sn, SiLi-Sn, SiPog’-Sn, Ls-E, Li-E, Ls-SnPon’, Stms-PP, Stmi-MP, Stms-PP/Stmi-MP and angle Z.RESULTS: After correction the patients’ maxillary and mandible bones achieved skeletal class I relationship, their first maxillary and mandibular molars achieved class I neutroclusion, the deep overbite and overjet were adjusted to normal state, the teeth centerline aligned, the average course of correction was 27.9 months; SNA increased 0.35°(P>0.05), which illustrated maxillary bones had the inhibition effect; SNB increased 3.23°(P<0.01), which illustrated mandible bones got the indirect stimulus effect; ANB decreased 1.81°(P<0.05), which was caused by the coordinating proportion of maxillary and mandible bones; both U1-NA and U1-SN decreased, which had the statistic difference(P<0.05); both L1-NB and L1-MP increased(P>0.05), which was in normal range of lip deformity; CmSn Ls increased 8°(P<0.05), which illustrated that the upper lip, compared with nose, was adducted; SiPog’-Sn increased 5°(P<0.01), which illustrated mental region grew forward; SnLs-Sn decreased 5.29°(P<0.05), Ls-E decreased 1.86(P<0.05)and Ls-SnPon’ decreased 2.14(P<0.05), which illustrated the upper lip was adducted; Si Li-Sn increased 8.14(P<0.01), angle Z decreased 5°(P<0.05), which illustrated mandible bones grew forward.CONCLUSION: During the period of growth peak of Adolescent’s skeletal classⅡ, the employment of cervical-headgear can inhibit the growth of maxillary bones as well as stimulate the growth of mandible bones indirectly so as to resolve the problem of uncoordinated condition of skeletal classⅡ. After correction, the rake of anterior teeth and lip can be improved to the extent that the anterior teeth can be adducted without any influence on the lower front teeth. The correction had significant effect on the improvement of important indexes, such as nasolabial angle, inclination angle of upper and lower lip, angle of chin groove, UL-EP,Ls-SnPg’,angle Z, which affect the soft tissues profile. Meanwhile, the correction also required to enhance the control of vertical. |
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