Orthodontic Force Modeling of Upper-Shape Loop Combined With Micro-Implant for the Treatment of Molar Arch Adduction

Malocclusion mainly manifested as crowded dentition and lordosis of the roof of the mouth. In order to treat malocclusion, it is necessary to guide and control the position of the teeth. Usually, the first premolars are removed to provide enough space for correction, and the upper-shape loop combined with micro-implant anchorage (USL-MIA) technology is adopted to achieve the purpose of adduction correction of the dental arch of the patient's oral grinding. In the treatment of malocclusion with USL or MIA, physicians rely on experience to approximate the magnitude and direction of the correction force generated by the USL or MIA deformation, and there will be bias. The purpose of this paper is to provide theoretical reference for doctors in the treatment of USL-MIA. The elastic deformation of the USL-MIA is analyzed, and the theoretical corresponding relationship between the USL-MIA deformation and the therapeutic force is calculated by using Castigliano's theorem so as to establish a theoretical model of the therapeutic force of the USL-MIA. In order to verify the accuracy of the theoretical model of correcting force, the theoretical value calculation, finite element simulation analysis, and experimental measurement of the archwire combined with MIA with different materials, section sizes, and section shapes were carried out. The correlation analysis of the obtained values shows that the Pearson correlation coefficient between the theoretical data and the simulation data is ${\xi }_A\ge 89.7\%$ , the Pearson correlation coefficient between the theoretical data and the experimental data is ${\xi }_B\ge 88.9\%$ and Pearson correlation coefficient between the simulation data and the experimental data is ${\xi }_C\ge 87.2\%$ . This model can help doctors to provide theoretical parameter support on the basis of original experience and can provide a faster and more convenient basis for doctors in orthodontic treatment and provide a safer treatment plan for patients.