Preliminary Clinical Study On The Three-dimensional Control Of Customized Suspension Devices For Traction Of Distal-extension Impacted Molars

Objective:3D printing technique was used to design and fabricate a customized suspension device to observe its clinical efficacy in the treatment of distal-extension impacted molars.Methods:We selected three patients(3 teeth)who came to the orthodontic department of the First Affiliated Hospital of Jinan University between 2016 and 2018 with different direction and location of distal-extension impacted molars.Before the treatment,CBCT and other clinical examinations were performed,then we reconstructed the digital dental model and finished the CAD design of customized suspension device.We 3D printed out the resin brackets,then proceeded with metal casting,polishing and cleaning to create the metal personalized suspension device(hereinafter referred to as the orthodontic device)In the clinic,the orthodontic appliance attached to patient's teeth is used with power chain for multi-dimensional traction to control the movement of the teeth in a three-dimensional direction and to observe and record changes in the position of the implanted molar.a customized traction device was designed according to the position of the molar.After treatment,the periodontal tissues of the tracted teeth were observed by CBCT,and the health status of the distal-extension impacted molars was evaluated in terms of root length,alveolar bone attachment height and periodontal tissues.Results:1.The use of 3D printing technology enables the fabrication of customized suspension devices that meet clinical practical needs2.The three cases with different clinical manifestations moved in a predetermined direction after the orthodontic devices were attached,suggesting three-dimensional control of three-dimensional control of buccolingual,vertical,mesial and distal orientation.3.CBCT revealed that the periodontal tissue of the implicated tooth was intact,the height of the alveolar bone was remodeled with the direction of tooth movement,the root was not resorbed and there was a tendency for continued growthConclusions:1.The customized suspension orthodontic device is suitable for the treatment of distal-extension impacted molars,with the advantages of easy operation,custom-made and precise 3D control2.Customized suspension appliances have advantages in the treatment of complex and difficult distal-extension impacted molars3.CBCT can effectively evaluate the periodontal condition of impacted teeth.The height of the alveolar bone of the trailed molar is remodeled as the tooth is moved;no resorption of the root is seen and there is a tendency to continue growth after the local resistance is removed.