Biomechanical Study On Distalization Impact Of The First Maxillary Molar Of The Different Eruption States Of The Second Molar And Different Anchorage

Objective To establish 4 groups of high-quality three-dimensional finite element model of The maxilla, dentition and micro-implant, analysing how to affect the first maxillary molar distalization by the different eruption status of the second molar and different anchorage ways, in order to provide theory evidence of Appropriate molar distalization time and anchorage for the clinic.Method Scan the Cranial specimens, establish Three-dimensional solid model of maxillary and teeth with software of MIMICS. Establish Three-dimensional solid model of Periodontal membrane,micro-implants, arch wires and brackets with software of I-DEAS.Carve up these models and establish Three-dimensional finite element model of the jaw, teeth, periodontal ligament, brackets, arch wire and micro-implant. Achieve Model 1,2,3,4 By computing. The four models Simulate different eruption states of the second molar and different anchorage method. To load 4 groups of Models and move the first molar,measuring the Initial displacement of the first molar, second molar and first premolar And observe the stress distribution of PDL.Results 1,Established 4 groups of high-quality three-dimensional finite element model of the maxilla, dentition and micro-implant and laid the foundation for further study. 2,The stress distribution of all models were similar. 3,In the case of the same load and different eruption state of the second molar, initial displacement of all data points of the first and second molar in the direction of X, Y, Z axiss showed: model 3> model 2> model 1. In the direction of Y axiss,the initial displacement of all data points about the first premolar showed: model 1> model 2> model 3. 4,In the case of two anchorage and different eruption state of the first molar, initial displacement of all data points about the first molar in the direction of X, Y axiss showed: load group 1> load group 4> load group 2 > load group 3. In the direction of Z axiss,showed: load group 1> load group 2> load group 3 > load group 4. In the direction of Y axiss, the initial displacement of all data points about the first premolar showed: load group 3> load group 2> load group 1 > load group 4.Conclusion 1,Three-dimensional finite element model founded by using thin spiral CT scan and software of MIMICS and I-DEAS had Good geometry, biomechanics similarity and laid the foundation for further study. 2,Moved when second molar was No eruption, first molar could get a faster travelling speed and better anchorage control,but lean and torsion of molar were more. 3,Second molar had the trend of buccal eruption when first molar was moved to distance. Clinicians should observe the tread of second molar eruption in the treatment and take steps in time if it erupt mistakenly. 4,Micro-implant enhanced anchorage best, but Classâ…¡traction could gain adjacent anchorage effect and faster rate of tooth movement in the case of the no eruption status of second molar relative to micro-implant. Clinicians may conside enhancing anchorage with classâ…¡traction to move molar in the case of the no eruption status of second molar, but we should take measures to avoid tilt and reverse movement at the same time. 5,Classâ…¡traction Caused the elongation of the first molar in the vertical direction. So we may consider enhancing anchorage with classâ…¡traction to move molar Disease in low-angle cases.But classâ…¡traction was Used with caution in high-angle cases. 6,Micro-implant and Classâ…¡traction have their advantages and disadvantages. Clinicians can select enhanced anchorage methods according to Economic situation of patients,Mandibular angle size,Face convexity And other factors.