| Objective:On the output model after the virtual teeth arrangement,the bonding position of the straight-wire appliance was quantitatively analyzed in order to initially investigate the teeth position where the straight-wire appliance bonding positioning deviates and the degree of deviation,thus providing an objective basis for the orthodontic clinic to improve the accuracy of the orthodontic appliance bonding.Methods:1.After a preoperative plaster model of orthodontic patient was selected for acceptance at the Department of orthodontics in the Affiliated Stomatological Hospital of Nanchang University,an oral scanner was used to scan the occlusion of the model.The scanned data was converted into a 3D digitization occlusion model of the patient at a scale of 1:1.2.Preparation of the study model: in this study,it was divided into a control group and an experimental group.Model preparation for the control group: the digital model data of the patient was exported in STL format to the accompanying orthodontic analysis software,3 Shape Ortho System,and then subjected to a virtual teeth arrangement.The teeth arrangement was done according to the six criteria of Andrews ideal occlusion.The results of the teeth arrangement were validated by three experts and the standard virtual model was generated,and 3D printing technology was used to produce a solid model for use as a backup.The participants of standard model preparation and bonding were 3 experienced orthodontic experts with senior professional titles in the department of Orthodontics,and the participants of experimental model bonding were 10 young and middle-aged doctors in the department of orthodontics.3.Experimental procedure:(1)A standard straight-wire appliance was bonded with light-curing resin on the standard model,with a total of 28 bonding units.Three experts jointly determined the bracket or buccal tube bonding position under direct vision in accordance with the standards of the straight wire orthodontic technique and then fixed it under light to generate the standard data model.The standard data model was scanned and imported into 3 Shape software to obtain three-dimensional data for each teeth position bracket or buccal tube positioning,i.e.the control group quantitative reference standard.(2)Experimental group: 10 young and middle-aged orthodontists were each fitted with the experimental group study model on a simulated head model and 280 bonding units of straight-wire appliance were bonded to the model with light-curing resin to generate the experimental group data model.The experimental group data model was scanned into the software system to extract quantitative indicators of the experimental group data model as experimental group data.Compare the experimental model data with the reference standard established by the standard model data.4.The indicators selected for evaluation in this study:(1)the distance from the centre of the bracket or buccal tube to the clinical dental crown tangent(occlusion)(Bc-Co);(2)the distance from the centre of the bracket or buccal tube to the distal mid-adjacent surface of the clinical dental crown(Bc-Cd);(3)the angle between the central axis of the bracket or buccal tube and the long axis of the clinical dental crown(Bc-Da).Results:1.The distance from the centre of the bracket or buccal tube to the clinical dental crown tangential(occlusion)margin(Bc-Co):the differences between the measurements of 13,16,17,23,26,27,33,36,37,43,46and47 in the measured values as well as the standard values were statistically significant(P < 0.05),while the measurements of the other teeth were not statistically significant.There was a statistically significant difference between the measured value of appliance bonding location and the standard value of Doctor 1 and Doctor 7(P < 0.05).2.The distance from the centre of the bracket or buccal tube to the distal mid-adjacent surface of the clinical dental crown(Bc-Cd):There were significant differences between the measured values of 15,16,17,25,26,27,33,34,37,43,44,47 and the standard values(p < 0.05),while the measurements of the other teeth positions were not statistically significant.There were significant differences between the standard values and the measured values of Doctor 1,Doctor 4 and Doctor 5(P<0.05).3.The angle between the central axis of the bracket or buccal tube and the long axis of the clinical dental crown(Bc-Da): There were significant differences between the measured values of model 12,16,22,25,26,35,37,42,45,47 and the standard values(P < 0.05),while the measurements of the other teeth positions were not statistically significant.There was no statistically significant difference between the measured value of appliance bonding location and the standard value of Doctor 9 and Doctor 10(P > 0.05),while the measurement values of appliance bonding location of other doctors and the standard values were statistically significant(P < 0.05).Conclusion:1.With the help of Computer aided measurement tools and digitization model,the accuracy of bonding positioning of the appliance can be intuitively quantified.2.Although young doctors have received traditional orthodontic training,there are still differences in the accuracy of the bonding and positioning of appliances,which are reflected in multi-dimensions: distal-medial and axial positioning deviation are more obvious.It is suggested that young orthodontists should be given targeted training to improve the accuracy of bonding and positioning of appliances. |
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