Three Different Methods Of Closing The Diastema Of Maxillary Incisors:a Three Dimensional Finite Element Study

ObjectiveTo construct the model of maxillary incisors dento-periodontal tissue before-treatment tissue based on the CBCT scan-image in order to study the basic biomechanics, and to function as a laboratory basis for improving clinical efficacy by analyzing the stress distribution of three therapeutic methods of closing the diastema of the maxillary incisors.MethodsUsing one adult patient’s oromaxillo-facial region CBCT scan-image data combined with Mimics10.01, Rhino3D NURB, Grasshopper and ANSYS12to construct maxillary incisors dento-periodontal tissue3D models, including a dento-maxillary model of upper incisors section, a matching bracketless invisible appliance model, a traditional fixed appliance model and a improved micro-button appliance model. Contact relations have been set between periodontium and teeth, teeth and bracketless invisible appliance, teeth and teeth. And analyze the stress distribution of teeth and periodontium by using nonlinear finite element method.ResultsAmong three different correction methods, teeth and periodontium loaded by bracketless invisible appliance has the max stress peak value, which is1.491MPa for teeth and4.100×10-2MPa for periodontium. Teeth, without contact to each other, and periodontium loaded by traditional fixed appliance has the minimum stress peak value, which is5.103×10-3MPa for teeth and1.774×10-4MPa for periodontium. Loaded by traditional fixed appliance, the instantaneous stress peak value of teeth was200times stronger than the teeth loaded by traditional fixed appliance, while for the situation of periodontium it was nearly300times stronger.Conclusion1. The instantaneous stress peak value of teeth and periodontium loaded by bracketless invisible appliance was obviously stronger than that of other two methods. The movement style was more similar to tilting movement.2. Periodontium loaded by traditional fixed appliance has the best uniform stress distribution.3. The movement, rotation, appearance and quality of teeth all have significant influence on the stress distribution of teeth and periodontium.