Objective: In the conventional orthodontic diagnosis, emphasis has often been placed on description of two-dimensional morphological characteristics. However, changes of growth direction and/or tooth position, as the results of our treatment are the biological response to the mechanical stimulus. To evaluate the biomechanical differences in malocclusion and mechanical effect of our therapy by three-dimensionally, we developed CBCT (cone beam CT) and patient specific biomechanical analysis.
Methods: With the measurement of EMG activity, biting force and structural information from CBCT, individual mechanical conditions were calculated by automated FEM (Finite Element Method). Distribution of mechanical energy, reaction force at Condyle generated by mastication, and center of occlusal curve (Spee curve) were evaluated in 12 malocclusions and normal subjects. In FE model, without any alteration of muscle loading, biomechanical optimum position and angulations of teeth were determined to generate the uniformed distribution of mastication energy, proper direction of reaction vector at Condyle and curvature of Spee, as the simulation of treatment.
Results: From the comparison among normal and malocclusions, differences in distribution of mechanical energy, direction of reaction force and occlusal curvature were clarified. The simulation of orthodontic tooth movement using FE model visualized one of the correct position of teeth and angulations of its axis to generate excellent biomechanical condition.
Conclusion: Orthodontic and Orthognathic treatment can change the occlusion and affect the mechanical condition in dento-maxillofacial region. Computational and biomechanical simulation using CBCT data could become a new powerful tool to predict optimum position of teeth as the individual treatment goal.