[Justification for the mandibular-maxillary order in bimaxillary osteotomy].

INTRODUCTION

Our aim was to study the reliability of sagittal split osteotomy and Le Fort I osteotomy respectively, and to try to judge objectively the impact of their order for the final result of bimaxillary osteotomy.

PATIENTS AND METHOD

Fifty patients were included. For each we calculated the errors generated by sagittal split osteotomies on one hand and Le Fort I osteotomy on the other hand, by performing a peroperative splint after each osteotomy.

RESULTS

After sagittal split osteotomies changes in the anteroposterior direction were present in 74% of cases with an average amplitude of 0.32mm. They were less frequent in the transversal direction, 54% of cases, with a smaller amplitude (0.19mm). After Le Fort I osteotomy, there was no difference in 92% of cases with an average error of 0.02mm in the anteroposterior direction. No errors were observed in the transverse direction.

DISCUSSION AND CONCLUSION

Le Fort I positioning is remarkably accurate contrary to the sagittal split. Using Le Fort I osteotomy first and mandibular sagittal split second has for drawback to perpetuate the errors of the sagittal split. The reverse order, beginning with the mandible, allows correction of sagittal split mistakes with the Le Fort I osteotomy. So it seems that the latter order is more logical and preferable.