Effects of Modeling Methods on the Finite Element Analysis Results of Orthodontic Applications

Yanzhi Liu, Purdue University


Identification of the mechanical environment changes in the tissues due to implementation of various treatment strategies are important for understanding the mechanism of the treatment outcomes, evaluating design of orthodontic appliances, and design of new treatment strategies. The goal of this study is to develop a finite element model that can be used to reliably estimate the mechanical environment changes due to various orthodontic treatment. The objectives are: 1) to build up a reliable model with details that can be more reliably utilized to simulate different orthodontic clinical cases, which will help orthodontists to predict the treatment outcomes, 2) to assess the significance of the differences between the simplified model and the models with more details, and (3) to apply the technology to clinical cases and estimate mechanical environment changes. A finite element model was created based on cone beam computed tomography (CBCT) images of an anonymous volunteer. The bone and teeth were segmented first. The finite element models were created using the geometries. The models were unique because the interfaces between the neighboring crowns and between the archwire and brackets were modeled using the contact elements, which allowed more realistic representation of the interfaces. The element size was determined through a convergence test. The validity of the stress was judged based on the calculated stress distribution. Then, the results of the new model were compared with these from a simplified model representing the studies published previously. The purpose was to see whether the simplified model can be used to replace a detailed model. Three clinical treatment strategies were modeled to evaluate the corresponding mechanical environment changes. The results showed that the new model produced more reasonable stress distribution than the simplified model. The simplified model resulted in much lower stress in the PDL than the detailed model, thus should not be used to quantify the stresses. The mechanical environment changes due to various treatment strategies provided useful information for studying the biological responses to the orthodontic load systems.




Chen, Purdue University.

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