Abstract: PURPOSE: This study was designed to establish a 3-dimentional finite element system to simulate the clinical scenario where labial segment was retracted with sliding mechanism in extraction cases treated by individualized lingual orthodontics. METHODS: A typical clinical case was selected. The subject was diagnosed with Class I malocclusion with alveolar protrusion and treated with extraction of 4 first premolars. The subject was under the treatment stage of frontal retraction by eBrace system, an individualized lingual appliance. The subject was also taken cone-beam CT (CBCT) based on which digital 3D reconstruction of dentition structures was formed with Mimics software. With the aid of software platform Pro/E 4.0, the important anatomical structures were defined, and relevant lingual devices, including lingual brackets, arch-wires, mini-screws and other accessories were formed. With the aids of software platform Geomagic Studio 13.0, the 3-dimentional structural mode, featuring maxillary alveolar, upper dentition, periodontal ligament, miniscrew and lingual applicance, were constructed. With the assistance of Ansys Workbench 15.0, 3D model for finite element system was finalised by conducting model meshing and defining the mechanical properties and the interface relations of the selected materials. RESULTS: Based on the digital information drawn from CBCT image, a 3-dimentional finite element system was successfully created, featuring all the elements mimicking the clinical scenario for En masse retraction. This system enabled an insight study on the effects of various retraction modes controlling the incisal torque and maintaining the dental arch integrity. CONCLUSIONS: The creation of a finite element system in this study is based on the digital data from the CBCT image of a real patient diagnosed with prognathic malocclusion and treated by lingual appliance. The clinical scenario of labial segment retraction via sliding mechanism is simulated in this finite element model.

Key words: Individualized lingual orthodontics, Finite element system, Force loading model, En masse retraction