Observation on Application Effect of Straight Wire Appliance and Invis-align Appliance in the Anchorage Demand of Tooth Extraction Patients with Malocclusion in the Alignment Stage

JIANG Yong; GU Yujia; CHEN Xue; WANG Tiancong

doi:10.3969/j.issn.1002-3429.2025.06.015

Abstract：Objective To compare the application effect of straight wire orthodontic appliance and Invisalign ortho-dontic appliance in the anchorage demand of tooth extraction patients with malocclusion in the alignment stage.Methods A retrospective analysis was performed on patients with malocclusion in anchorage demand in the alignment stage of tooth extrac-tion from July 2019 to September 2023.According to different orthodontic methods,they were divided into straight wire group(using straight wire appliance)and invisible group(using Invisalign appliance).Propensity matching method was used to ex-clude the confounding factors of baseline data;thus,there were 60 patients in each group.The plaster model of the two groups was scanned by iTero scanner and the three-dimensional(3-D)model was reconstructed.The 3-D model overlap was used to measure the changes of each parameter.The 3-D model overlap measurement values before and after alignment,jaw bone changes(FMA angle,IMPA angle,FMIA angle,ANB angle),soft tissue changes(UL To E Line,LL To E Line),tooth changes(U1-NA,L1-NB)and complications were compared between both groups.Results The measurement values of U1X,U3Y,U3 torque and U5 tilt angle overlap after alignment in invisible group were significantly lower than those in straight wire group,while the U3X,U5X,U5Y,U5Z,U6X,U6Y,U6Z,U1 torque,U5 torque,U6 torque,U3 tilt angle and U6 tilt angle were significantly higher than those in straight wire group(P＜0.05,P＜0.01).After alignment,the FMA angle,IMPA angle,and ANB angle in both groups significantly increased,while the FMIA angle significantly decreased,compared with those before alignment(P＜0.05).After alignment,both groups showed a significant decrease in UL To E Line and LL To E Line,as compared with that before alignment(P＜0.05).After alignment,U1-NA in both groups de-creased significantly,while L1-NB increased significantly,U1-NA in the invisible group was significantly lower than that in the straight wire group,while L1-NB was significantly higher than that in the straight wire group(P＜0.05).There was no significant difference in the total incidence rate of complications between invisible group(3.33%,2/60)and straight wire group(6.67%,4/60)(P＞0.05).Conclusion Both straight wire orthodontic appliances and Invisalign orthodontic appli-ances can be used to meet the orthodontic needs of tooth extraction patients with malocclusion during the alignment stage.However,there are some anchorage loss in both methods,and the clinical treatment plan should be reasonably selected.