Influence of the mandibular plane and magnitude of the movement in sagittal split ramus osteotomy: an in vitro study.

PURPOSE: The aim of this study was to evaluate fixation resistance in mandibular sagittal split ramus osteotomy in standardized polyurethane hemimandibles with two types of advancement (6 and 12 mm), with or without mandibular plane rotation, using a 2.0-mm plate/screw system.

METHODS

Seven groups were evaluated using a vertical compressive load in the first molar region, and the applied force in Newtons was recorded in 1 mm, 5 mm, and 10 mm displacements, as well as the maximum force.

RESULTS

There was a statistical intergroup difference and it was observed that increasing the advancement decreased fixation resistance with a single plate, and inserting an additional plate significantly increased osteosynthesis resistance.

CONCLUSION

In the 12 mm advancements, clockwise rotation proved to be more resistant when fixed with only one plate. By contrast, counterclockwise rotation was significantly more resistant in stabilizing the mandibular sagittal ramus osteotomy when two plates were used.