[Three-dimensional finite element analysis of mandibular bilateral sagitta1 split ramus osteotomy with rigid internal fixation].

PURPOSE: To study the biomechanical characteristics of mandibular bilateral sagittal split ramus osteotomy(BSSRO) fixed with absorbable plate or titanium plate.

METHODS

Spiral CT scan and finite element software (Ansys)were used to establish the three-dimensional finite element model of BSSRO with absorbable plate or titanium plate. The stress distribution of the internal fixation and the displacement of splited mandible was calculated under three kinds of occlusion position.

RESULTS

Under the same occlusion,the maximal displacement of splited mandible was basically similar.The maximal stress of fixation system was titanium plate > absorbable plate; double plates > single plates; superior plate > inferior plate in the double plates. With the same fixation mode, the maximal stress of the fixation system and the maximal displacement of splited mandible was incisor occlusion<premolar occlusion <molar occlusion.

CONCLUSIONS

The stress shielding of internal fixation of double plate is greater than single plate. Rigid internal fixation materials has certain impaction on stress shielding, but titanium plate is greater than the absorbable plate. Incisor occlusion had significant harmful effects and should be avoided after surgery.