Invisible Bracketless Correction Of Adult Class Ⅱ Division 2 Malocclusion Study On Torque Efficiency Of Upper Central Incisor

Objectives:Through Cone Beam Computerized Tomography(CBCT)combined with 3D reconstruction imaging of the interactive medical image control system(Materialise’s Interactive Medical Image Control System,MIMICS),Geomagic Studio reverse engineering software overlap analysis and Dophin Imaging software,the research adopts hidden imaging After the design of the digital program of the Invisible Brackets without brackets,the adult patients with Class Ⅱ division 2 malocclusions were corrected,and the upper central incisor torque control movement efficiency expression,tilt change,and alignment of the upper central incisor root and alveolar before and after treatment The influence of bone provides experimental data and reference basis for the design of this kind of malformation and deformity.Methods:1.Selected 20 cases of adult with Class Ⅱ division 2 malocclusions and who were treated at the Orthodontics Department of the Affiliated Stomatological Hospital of Kunming Medical University from September 2018 to December 2019,and treated with the Invisalign Bracketless Invisible Orthodontics.2.The design of the plan is:the upper anterior teeth lip pressure is lowered,and the molars are moved far to obtain the space to align the upper dentition,and it is planned to move the root tongue to the crown lip to torque root control.3.Measurement items:(1)Analysis of movement efficiency:measure the actual movement amount and target movement amount of the crown and root of the upper central incisor,using the formula:movement efficiency=actual movement amount/target movement amount × 100%,calculate the crown and Root movement efficiency;(2)Changes in the inclination of the upper central incisor:including changes in the angle of the upper central incisor relative to the SN plane and the NA plane,and changes in the distance between the upper central incisor’s incisal edge and the NA plane;(3)through Cone beam CT measures the changes in root length before and after treatment,and statistically analyzes the changes in root length;measures the changes in alveolar bone thickness on the lip and tongue side of the root neck L1,mid-root L2,and apex L3 before and after treatment,and analyzes the use of invisible brackets without brackets The thickness of the alveolar bone on the labial and lingual sides of the upper central incisor was changed before and after correction.4.Statistical analysis method:SPSS23.0 was used for statistical analysis.After the normality test,the paired t test was used to study the normality test,and the Wilcoxon rank sum test was used for the non-conformity.Results:1.Measure the actual movement of the crown and root of the upper central incisor before and after treatment and the target movement in ClinCheck.The average target movement of the crown and lip is 1.904±1.135(mm),and the actual movement is 1.480±.1.033(mm),the average moving efficiency of 70.18%;the average target moving distance of the root tongue is 4.173±1.821(mm),the average actual moving distance is 2.160±1.087(mm),and the average moving efficiency is 51.16%.The actual amount of movement and the target amount of movement are significantly different(P<0.001);2.After treatment,the measured values of U1-SN(°),U1-NA(°),and U1-NA(mm)increase,and there are Significant statistical difference(P<0.001),suggesting that the invisible correction without brackets is effective,and the upper central incisors return to normal inclination;3.Measurement and analysis of the root length before and after treatment of 40 upper central incisors in 20 patients,and the length of the front and back roots There was a significant statistical difference(P<0.001).Among them,9 had no root resorption,3 had moderate resorption,28 had light resorption,and no severe resorption.The average root resorption was 0.452±0.493(mm);4.Treatment There were statistically significant differences in the thickness of alveolar bone in the anterior and posterior neck,mid-root and apical areas(P<0.05),the amount of alveolar bone on the labial side increased,and the amount of lingual alveolar bone decreased.Conclusions:Mimics 3D modeling combined with Geomagic Studio reverse engineering software can realize the analysis and research of the movement of the crown and root of the upper central incisor;the invisible braces without brackets can realize the movement of the tongue to the crown and the lips,and effectively correct the upper central incisor.Introversion;Invisible orthodontic bracketless invisible appliance has root resorption of the upper central incisor,but the absorption is small,and the thickness of the lingual alveolar bone is reduced after the tooth moves;the precise tooth movement design can better control the tooth movement,Provide patients with safer and more effective orthodontic treatment options.