| Objective The aim was to study the influence on smile and the relevant factors by extraction and myofunctional therapy,following by analyzing the changes pretreatment and posttreatment frontal smiling photographs and cephalometrics with skeletal class Ⅱ malocclusion after extraction treatment.Methods Select twenty permanent dentition patients of skeletal class Ⅱmalocclusion by the standard,5°≤ANB angle≤9°(Mean 6.45°±1.50°),19°≤SN-MP angle ≤50°(Mean 36.85°±7.63°),aged from 13 to 28years(Mean 17.79± 4.48 years old).All subjects had been treated with maxillary and mandibular straight-wire technique by extraction and use additional enhancements palatal measures,such as the TPA and MIA implanted.Frontal smile photographs and cephalometrics were taken before and after treatment with clear landmarks of both hard and soft tissues.X-ray films cephalometric(including Angle of SNA,Angle of SNB,Angle of SN-MP,Angle of U1-SN,Angle of U1-NA,Angle of L1-NB,etc.)and the frontal smile Photographs were measured with Adobe Photoshop CS7(including curvature of forward tooth,lower lip curvature,buccal corridor,smile width,smile height,,smiling arc and upper lip shape,etc.),All of measurements were analyzed by SPSS version 17.0,the data measurement of chances with smile and cephalometrics by treatment matching Paired t test,the chance of smile arc and upper lip form compared by chi-square test,the chance of correlation was comparison using Pearson correlation analysis,which beteen smile and the structure of cranial jaw teeth after treatment.Results 1.Comparison of X-ray cephalometric measurement of craniofacial structures before and after orthodontic treatment: After treatment∠SNA and∠ANB were decreased,∠U1-SN and ∠U1-NA and ∠ L1-NB were decreased.The upper and lower lip were adducted than the aesthetic plane respectively.These parameters showed statistically significant(P<0.05).2.Comparison of the related indexes of the beauty smiling before and after orthodontic treatment: After treatment,curvature of upper incisor was increased,The difference between curvature of upper incisor and lower lip was reduced,Buccal space ratio increased,Upper incisor ratio increased,Exposure of lower incisors was decreased,These parameters showed statistically significant(P<0.05).3.Comparison of the change of the smile arc shape and upper lip curvature before and after treatment: After treatment,the number of ideal smile arc increased significantly,The number of upward upper lip curvature increased significantly,The number of parallel smiling arcs was significantly reduced,The difference was statistically significant(P<0.05).4.The result of analysis of the correlation between the cephalometric measurement of the craniofacial structure and the measurement of smile: There was a negative correlation between the change of ∠U1-SN and the change of the curvature change of upper incisor,There was a positive correlation betweenthe change of ∠U1-SN and the change of the difference between curvature of upper incisor and lower lip,There was a negative correlation between the change of ∠U1-NA and the change of curvature of upper incisor,There was a positive correlation between the change of ∠ U1-NA and the change of the difference between curvature of upper incisor and lower lip,There was a negative correlation between the change of ∠SN-MP and the change of buccal space ratio.Conclusion 1.The front and profile of facial tend to more harmonious after extraction in permanent dentition patients of skeletal class Ⅱmalocclusion.The vertical height had no obvious changes,lip-teeth relationship improved by upper incisors retraction.2.The permanent dentition patients of skeletal class Ⅱ malocclusion was treated with smile myofunctional therapy,smile measurement were improved after treatment,smiling arc incline to coordinate,upper teeth exposure were increased,lower teeth exposed were decreased,buccal corridor and the symmetry of smile were increased,smile charm is worth to ascend.3.The changes of Smile arc were correlated with changes of upper incisors inclination.The changes of buccal corridor were correlated with changes of the vertical height.Tips in the orthodontics process of design and treating should be combined with patient,s smile appeal,treated with smile myofunctional therapy,making the change of maxillofacial and smile work together,to he purpose of enhance the connotation of orthodontic and traising the overall level of orthodontics. |
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