| In the process of orthodontic diagnosis and treatment plan,it is important to evaluate the sagital position relation index accurately,and the clinical evaluation on mandibular sagittal position measurement index includes various angle and linear index which are commonly used,such as ANB angle,Wits appraisal,Beta angle,the APDI index,etc.However,each index has its own disadvantages.A new evaluation index of the sagittal position relationship of the maxilla and mandibles,W angle,has been proposed in recent years.In our study,we analyzed the lateral cephalometric X-ray of Xi’an Han nationality adult individual in order to find out the distribution range of W angle of the normal value and the distribution range in skeletal Class Ⅰ,Class Ⅱ and Class Ⅲ malocclusion patients,and try to evaluate the accuracy of the W angle used in different sagittal skeletal malocclusion diagnosis.Experiment one: Extraction of normal W angle values of adult in Xi’an Han Adults with normal occlusionObjective: To analyze the distribution range of W angle in normal adults of Han nationality in Xi’an area,and find out whether there is difference between male and female with normal occlusion,in order to provide reference for clinical diagnosis and analysis.Methods: 120 patients with normal occlusion(60 male and female)were selected from Xi’an Han adults(age:18-30).The values of W angle were measured on the lateral cephalometric X-ray,and the difference of the W angle values between male and female groups was analyzed.Results: The mean value of the W angle in Xi’an Han male adult with normal occlusion was 59.94 degrees with SD of 4.21,whereas the mean values in female was 58.03 degrees with SD of 2.90.There was no significant difference between the groups of men and women(P>0.05).Combined the data of the male and the female groups,the mean values of W angle for adult with normal occlusion in Xi’an area was58.87 degrees with SD of 2.41.Experiment two: Study on the distribution and difference of W angle in adult sagittal to different malocclusion individualsObjective: To establish the reference range of W angle in different sagittal individuals of Han nationality in Xi’an area,compare the difference of W angle values between different malocclusion,and further analyze the characteristics of W angle,so as to provide reference for clinical diagnosis and analysis of sagittal position relationship of occlusion.Methods: 180 patients(age:18-30)with malocclusion were chosed from The Fourth Military Medical University stomatology hospital from 2014 to 2017.All patients were divided into three groups: Class Ⅰ malocclusion(0.7 degrees≤ ANB ≤ 4.7 degrees,Wits appraisal:-10.5mm ~-0.5mm,30 male and 30 female);Class Ⅱ malocclusion(ANB > 4.7degrees Wits appraisal:-10.5mm ~ 8mm,30 male and 30 female);Class Ⅲ malocclusion(ANB < 0.7degrees Wits appraisal: 0mm ~ 8mm,30 male and 30 female).W angle was measured in cephalometric radiographs,and analyze the differences of the W angle in the different sagittal skeletal pattern.Results:(1)The mean value of the W angle in Class Ⅰ malocclusion male was 57.99 degrees with SD of 3.11,whereas the mean values in Class Ⅰ malocclusion female was 58.13 degrees with SD of 2.88.The mean value for the W angle in Class Ⅱ malocclusion male was 55.34 degrees with SD of 3.46,whereas the mean values in Class Ⅰ malocclusion female was 54.96 degrees with SD of 2.25.The mean value for the W angle in Class Ⅲ malocclusion male was 66.76 degrees with SD of 5.16,whereas the mean values in Class Ⅰ malocclusion female was 63.25 degrees with SD of3.46.there were no gender differences between men and women group(P>0.05),so it can be combined with the calculation.The mean value for the W angle in Class Ⅰ malocclusion was 58.07 degrees with SD of 2.96,the mean value for the W angle in Class Ⅱ malocclusion was 55.12 degrees with SD of 3.48,the mean value for the W angle in Class Ⅲ malocclusion was 64.85 degrees with SD of 4.84.(2)One-way analysis of variance showed that the difference between the normal occlusion group and skeletal Class Ⅰ group W angle was not significant(P>0.05),and there were significant differences between the normal occlusion group and the skeletal class Ⅱ group,the normal occlusion group and the skeletal class Ⅲ group,the skeletal class Ⅱ group and the skeletal class Ⅲ group,the skeletal class I group and the skeletal class Ⅱ group,the skeletal class I group and the skeletal class Ⅲ group(P ?0.05).Experiment three: Analysis of diagnostic accuracy of W angle for different types of malocclusionObjective:To evaluate the relationship between W angle and other five indexes,including ANB angle,Wits appraisal,APDI index,Beta angle and YEN angle,and analysis the accuracy of W angle in the diagnosis of different sagittal malocclusion.Method : 300patients(age:18-30)with malocclusion were chosed from The Fourth Military Medical University stomatology hospital from 2014 to 2017,with an average age of 23.4 years.W angle,ANB angle,Wits appraisal,APDI index,Beta angle,YEN angle values were measured in the lateral cephalometric radiographs.The distribution range of the six indexes were analyzed and the degree of overlapping was calculated in order to evaluate the accurancy of these indexes.Conclusion:(1)The diagnostic accuracy of these indexes in class Ⅱ : W angle> YEN angle> Beta angle>APDI index>ANB angle> Wits appraisal.The diagnostic accuracy of these indexes in class Ⅲ: ANB angle>APDI index>W angle>YEN angle>Beta angle> Wits appraisal.(2)The degree of overlapping of W angle was 0.104 between Class Ⅰ group and Class Ⅱ group,and the degree of overlapping of W angle was 1.21 between Class Ⅱ group and Class Ⅲ group.This indicates that for the diagnosis of Cass Ⅱ malocclusion,the diagnostic efficiency of W angle is the highest,and it has obvious advantages in evaluating skeletal Class Ⅱ malocclusion.For the diagnosis of Class Ⅲ malocclusion,the diagnostic efficiency of W angle is lower than that of ANB angle and APDI index.ANB angle has the highest diagnostic efficiency in evaluating Class Ⅲ malocclusion. |
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