| Objective By establishing without braces stealth correctional implement three-dimensional finite element model,simulating clinical far in the moving process of treatments of the maxillary canines,analysis and discussion on different diaphragm after combination of double film hardness and hardness of the combination of double membrane combined with vertical rectangular attachments and single hardness of treatments without braces contact diaphragm far maxillary teeth with the trend of stress distribution and displacement of teeth,To provide basis for clinical design of invisible correction technology.Methods The maxillary data were obtained by cone-beam CT scanning of the volunteers’heads that met the experimental conditions,and saved in DICOM file format.Finite element models of cusp,alveolar bone,periodontal membrane and buttonless invisible orthodontic device were established by using Mimics,Geomagic and Abaqus finite element software.Three groups were set up for simulating different invisible orthodontic distal canines with 0.15mm without brackets and different hardness combinations without attachments:A:inner soft film 0.2mm and outer hard film 0.6mm;B:Inner soft film 0.4mm,outer hard film 0.4mm;C:inner soft film 0.6mm,outer hard film 0.2mm,with attachments of different hardness combination of double film set three groups:D:vertical rectangular attachment with inner soft film 0.2mm,outer hard film 0.6mm;E:vertical rectangular attachment with inner soft film 0.4mm,outer hard film 0.4mm;F:vertical rectangular attachment combined with inner soft film 0.6mm,outer hard film 0.2mm,among which the elastic modulus of soft film of double film group is 415.6Mpa,the elastic modulus of hard film is 2400Mpa.Single film group with different hardness without attachments is set in three groups:G:film thickness 0.8mm,elastic modulus of 415.6Mpa;H:Diaphragm thickness 0.8mm,elastic modulus 816.3Mpa;I:Diaphragm thickness 0.8mm,elastic modulus 2400Mpa.In order to analyze the displacement trend of maxillary cusp and the stress distribution characteristics of periodontal membrane,six nodes were selected from crown to root on the central axis of the distal surface of maxillary cusp.Results The maximum compressive stress of group B was distributed near the palatal midface and neck margin,and the movement mode was far slanting,with the direction of the tongue and the tongue and the movement was low.The stress distribution of group B was more uniform than that of group A and GROUP C.The maximum principal stress on the proximal and distal surfaces of the teeth in the double-membrane group with attachments was uniform,and the cusp showed overall movement.The stress and movement trend of the teeth in group E were the best when the thickness of soft and hard membranes was the same.In group 3,the maximum principal stress was distributed near the medial and cervical margin of the palatal side,and the cusp presented an uncontrolled oblique movement with a trend of coronal-palatal orientation and depression.With the increase of hardness,the stress peak increased gradually.In group I,the overall stress distribution was more uniform,but the control ability of the root was weak.Conclusion Compared with the single diaphragm appliance,the double diaphragm appliance has a more uniform distribution of the orthodontic force and is more beneficial to the health of the periodontal membrane in the process of tooth movement.Moreover,the double film appliance combined with different hardness and thickness of the diaphragm can control the movement of the tooth more flexibly and achieve ideal therapeutic effect.At the same time,the double diaphragm clinchless invisible appliance combined with vertical rectangular attachment can effectively control the root movement in the process of tooth movement.With the increase of the hardness of the single film,the orthodontic force also increases,but when the hardness of the film reaches a certain degree,excessive orthodontic force may cause certain damage to the periodontal tissue,and there is a potential risk... |
PDF Full Text Request