A Comparative Study Of The Changes Of Vertical Direction Before And After Orthodontic Camouflage Treatment Of Adult Skeletal Class Ⅲ Malocclusion

Objective:Based on the analysis of the lateral cephalometric film before and after the treatment of adult skeletal class Ⅲ malocclusion orthodontic camouflage therapy,the patients were divided into high-angle group and average-angle group to explore adult skeletal class Ⅲ malocclusion patients before and after orthodontic camouflage therapy,the changes of vertical indicators such as Occlusal plane,mandibular plane and the related relationships,to provide the theoretical basis for the control of vertical anchorage in clinical application.Methods : A retrospective analysis of the clinical correction data of 32 adult skeletal Class III malocclusion patients who were admitted to the Orthodontics Department of the Second Affiliated Hospital of Dalian Medical University.All patients were treated with straight wire appliances and multi-curved square wire appliances.Among them,14 were males and 18 were females,aged 18-33 years old,with an average of(22.24±3.63)years old.These patients were divided into high-angle group and average-angle group according to the eye-ear plane-mandibular plane angle(FMA)in the Tweed analysis method.Among them,the average-angle group 22°≤FMA≤ 28°,17 cases in total,the high-angle group FMA>28°,a total of 15 cases.All patients with high angle use maxillary transpalatal arch(TPA).32 patients’ pre-treatment and post-treatment lateral cephalograms were scanned using the Vceph 5.0 software.The representative parameters included 17 items which described the vertical changes before and after treatment,such as occlusal plane,mandibular plane,etc.All lateral cephalograms were measured by the author using Vceph 5.0 software at the same time.The measurement was repeated every other week for a total of three measurements and the average value was taken.Line distance measurement accuracy was 0.01 mm,angle measurement accuracy was 0.01 °.The vertical changes data before and after treatment was collected and SPSS23.0 software package was used for statistical analysis.Analyzed the change of vertical indicator of skeletal Class III malocclusion with different facial vertical skeletal patterns,and whether the difference between the two groups was statistically significant.Each measurement value before and after the treatment in the group was subjected to the paired sample t test within the group,the difference in changes before and after treatment between the two groups was performed by independent sample t test,P < 0.05 indicates that the difference was statistically significant.Results:Comparing the high angle group and the average angle group patients before and after treatment,SNB,Occlusal plane,Po-N Perpend decreased,ANB,AB-MP,OP-MP increased,and there were statistical differences(P< 0.05);SNA,FMA,SN-Go Gn,Y-axis to SN increased slightly,Ramus height,Po to NB decreased slightly,but there was no statistical difference(p>0.05).Before treatment,the SNB of the average angle group was larger than that of the high angle group,and there was a statistical difference(p<0.05);the average angle group ANB,SN-Go Gn,Y-axis to SN,and Occlusal plane were smaller than the high angle group,and there was a statistical difference(P< 0.05);there is no statistical difference in other indicators.After treatment,the SNB of the average angle group was greater than that of the high angle group,and there was a statistical difference(p<0.05);the average angle group ANB,SN-Go Gn,Y-axis to SN,Occlusal plane,and ANS-Me/N-Me were smaller than the high angle group,There is a statistical difference(p<0.05);the other indicators are not statistically different.Conclusion : 1.Although orthodontic camouflage treatment can make the mandible move back and coordinate the sagittal relationship between the maxillary and mandibular,it cannot change the class Ⅲ skeletal pattern.Only orthodontic-orthognathic combined treatment could completely solve the skeletal problem.2.Comparing the two groups of patients before treatment,the average angle patients with higher chin angle are more prominent,indicating that there is a certain degree of compensation in the sagittal direction in the skeletal class Ⅲ high angle patients.3.High-angle patients can also control the vertical height and the angle of the mandibular plane well with a reasonable anchorage design.