Objective: To identify the best loading angle with Forsus for mandible-temporomandibular joint.
Methods: The changes in stress, displacement and rotation of "mandible-temporomandibular joint" were tested under -30 degrees, -15 degrees, 0 degrees, 15 degrees and 25 degrees of loading angles using a primary three dimensional finite element model.
Results: From 0 degrees to 25 degrees, with the increases of loading angles the displacement gradually increased. The maximum displacement occurred at chin, with 1.692 mm, 3.456 mm and 4.630 mm displacement under 0 degrees, 15 degrees and 25 degrees respectively. The maximum displacement occurred at the alveolar ridge under -15 degrees loading, which was 0.069 mm. No special stress concentration region was identified. The displacements from infradentale to pogonion gradually increased under all conditions except for the -15 degrees loading. With the loading angles deviated from the baseline farther, the porrect displacements of chin and the counterclockwise rotation became more obvious.
Conclusion: The loading angles of Forsus appliance should be controlled between 0 degrees and 25 degrees.