OBJECTIVETo further explore the best Forsus load power by analyzing the change of mandible's stress and displacement after Forsus protruded mandible instantaneously under different vertical component for providing theoretical basis.

METHODSThe pre-built Forsus protruding mandible model were build through Abaqus 6.5 software. The change of mandible's stress, displacement, and pathway trend under three different working conditions(horizontal component 4 N and vertical component 2, 4, 1 N).

RESULTSTorsion occurred in all condyles under three working conditions, and the stress was large. Under vertical component 2 and 1 N, the mandible demonstrated counterclockwise rotation, the maximum displacement occurred in the chin, respectively 1.150 mm and 2.141 mm; under vertical component 4 N, mandible rotation was not obvious, the maximum displacement of chin was only 0.188 mm.

CONCLUSIONWith the vertical component gradually decreased, the protrusion trend of chin increased; Forsus could promote the mandible counterclockwise rotation and modification when protruding mandible.