Stability of the miniplate osteosynthesis used for sagittal split osteotomy for closing an anterior open bite: an...

Bilateral sagittal split osteotomy of the mandible with counterclockwise rotation of the occlusal plane alone has traditionally been considered the least stable treatment method. Two miniplates on each side of the osteotomy may resolve this problem. The authors compared early vertical and transverse stability of a simple mandibular advancement (group A), mandibular advancement with counterclockwise rotation (CCW) stabilized with one miniplate (group B), and two miniplates (group C) on mini-pig mandibles mounted on a custom-made loading unit. Two miniplates markedly increased the resistance to vertical bite forces. On a 100-N load, a median of dislocation of 0.53 mm, 0.46 mm, and 0.23 mm was achieved in groups A, B, and C, respectively. The difference was statistically significant between groups A and B in comparison with group C. The results of transverse displacement were not statistically significant. The use of two miniplates in larger shifts, as well as in CCW cases, increases stability in the vertical direction.